CARNIVOROUS PLANT
NEWSLETTER
Journal of the International Carnivorous Plant Society
Volume 44, No. 4
December 2015
CARNIVOROUS
PLANT
NEWSLETTER
Journal of the International
Carnivorous Plant Society
www.carnivorousplants.org
Volume 44, Number 4
December 2015
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Carnivorous Plant Newsletter
Contents
Several pygmy Sundew species possess catapult-flypaper traps with repetitive function,
indicating a possible evolutionary change into aquatic snap traps similar to Aldrovanda — 172
Soil pH values at sites of terrestrial carnivorous plants in south-west Europe — 185
Is long-term survival of dried turions of aquatic carnivorous plants possible? 189
Literature review - 194
Hypothesis of mucilage-assisted dispersal of Drosera seeds 195
Photoperiod regulates Cape Sundew ( Drosera capensis) gland secretion and
leaf development- - - — 197
Second brief piece of information about the species status of Utricularia cornigera Studnicka — 204
How hungry are carnivorous plants? An investigation into the nutrition of carnivorous
plant taxa from the Kimberley region of Western Australia 207
New cultivars — 213
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Volume 44 December 2015
171
Technical Refereed Contribution
Several pygmy Sundew species possess catapult-flypaper traps with
REPETITIVE FUNCTION, INDICATING A POSSIBLE EVOLUTIONARY CHANGE INTO
AQUATIC SNAP TRAPS SIMILAR TO ALDROVANDA
Siegfried R. H. Hartmeyer and Irmgard Hartmeyer • Weil am Rhein • Germany • s.hartmeyer@
t-online.de • www.hartmeyer.de
Keywords: Drosera, pygmy Sundew, Aldrovanda, Dionaea, Droseraceae, Collembola, carnivorous
plant, catapult-flypaper trap, snap trap, snap-tentacle, functional morphology, phylogeny.
Abstract: Approximately 50 species of pygmy Sundews (genus Drosera , section Bryastrum ) occur
in the South of Australia and one each in New Zealand (D. pygmaea) and Venezuela (D. meristo-
caulis). They grow mainly as small stemless rosettes possessing minute trapping leaves of 1-2 mm
diameter with prominent marginal tentacles, or have elongated erect stems. The caulescent species
possess only mucus-producing tentacles that are most effective in capturing small flying insects.
The acaulescent species in contrast are specialized on crawling prey (Verbeek & Boasson 1993)
and have developed mucus-free snap-tentacles (Fig. 1), able to bend surprisingly rapidly towards
the leaf center. They lift prey like, e.g. springtails (Collembola) from the ground and carry it with a
1 80°-movement from the periphery of the plant onto the sticky leaf. Our examinations brought to
light that several small species of section Bryastrum are able to catapult small animals even within
fractions of a second. If the whole leaf is touched, several or even all marginal tentacles perform such
bending movements simultaneously. We documented this behavior on video, featured on our film
“Catapults in Pygmyland” on YouTube ( w w w. yo ut ube . com/ watch? v=5k7GY Gibdj M ) . Our results
prove that more than only one species in the genus Drosera possess rapidly moving catapult- flypaper
traps and that the examined pygmy catapults show a further specialization and function repeatedly
(in contrast to the one-shot snap tentacles of D. glanduligera). The mucus-free and rapid catapult-
mechanism functions independent from the initially slow mucilage-based trapping. Furthermore,
our study demonstrates that in contrast to
D. glanduligera , each single pygmy cata-
pult possesses a similar sensor system and
hydraulically operated motion-sequences
analogous to the lobes of snap-traps. Cat-
apult-flypaper traps submerged in water,
forming a kind of grid-cage when triggered
simultaneously could be able to capture prey
underwater even without any mucilage. This
is a possible scenario for the development
of aquatic snap traps similar to Aldrovanda.
Catapult-flypaper Traps
Very rapid catapulting tentacle move- Figure 1: Drosera callistos with springtail
ments have only previously been reported below the front snap-tentacles.
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Carnivorous Plant Newsletter
in the annual D. glanduligera (section
Coelophylla), a close relative of the pygmy
Sundews (Hartmeyer & Hartmeyer 2005).
These movements, which occur in fractions
of a second, are comparable in speed with
those of Dionaea and Aldrovanda. In 2012,
we were able to prove in a common project
with the Plant Biomechanics Group of the
Botanic Garden of the University Freiburg,
using a high-speed camera, that D. glandu-
ligera utilizes its protruding snap-tentacles
to catapult fruit flies ( Drosophila ) within
75 milliseconds (Fig. 2). Activated by the
prey’s impact, the hit glue-tentacles on the
lamina lift the victim within 1-2 minutes
into a particularly pronounced patelliform
digestion cavity in the leaf center, able to contain 3-4 Drosophila. It is a hydraulically driven co-
ordinated two-stage capture mechanism, for which we coined the designation catapult-flypaper
trap (Poppinga et al. 2012). The catapults of D. glanduligera function only once because cells in
the hinge-zone burst during the movement through compressive stressing. A slight touch of the
tentacle head is sufficient here to trigger a complete bending with maximum speed after a response
time of 400 milliseconds. The mucilage producing tentacles show a uniform response time of 8-12
seconds after touching or prey impact. A conspicuous feature of this trap type is that only stimu-
lated tentacles move while the leaf itself remains immobile, it does not curl around the prey. The
aim of this study was to determine if tentacles in the pygmy Sundews with a structure similar to D.
glanduligera react with the same rapidity and exhibit the same behavior as this catapult-flypaper
trap and to determine how wide spread this behavior is within this branch of the Droseraceae. For
our experiments, we had approximately a dozen plants each of D. glanduligera (section Coelo-
phylla) and 20 pygmy Sundew species (all section Bryastrum) available: D. androsacea, D. callistos
“Brookton”, D. dichrosepala, D. helodes, D. echinoblasta , D. eneabba, D. enodes, D. lasiantha, D.
leucoblasta, D. mannii, D. microscapa, D. miniata, D. occidentalism D. platystigma, D. pulchella ,
D. pycnoblasta, D. pygmaea “Australia”, D. roseana, D. scorpioides, and D. walyunga. In addition,
Gideon Lim from Malaysia kindly provided us his video of the rapid catapulting action of the all
green New Zealand variety of D. pygmaea.
Materials and Methods
We propagated the annual D. glanduligera from seeds. Most of the perennial pygmies were only
some 8-10 weeks old and grown from gemmae. Some plants are part of our collection since several
years (see Table 1). All plants thrived inside our cool greenhouse in Weil am Rhein (Germany ) in a
southwest location with night temperatures of 4-12°C and 12-26°C during the day. From October to
April, we added a 400W HQI-lamp for ten hours daily to complement the low sun intensity during
winter. As a reference, some plants thrived inside an adjacent tropical greenhouse with night tem-
peratures of 14-18°C and 22-3 0°C during the day, applying two 400 W HQI-lamps during the same
months as mentioned above. Videos and photos: Sony Z5 HDV camera (PAL) with Sony G-Lens.
Lumix MH DMC-TZ 10. Microscope: Wiloskop F Zoom (Hund Wetzlar), magnification 13.4-180
Figure 2: Drosera glanduligera with just flung
fruit fly.
Volume 44 December 2015
173
Table 1. Drosera species examined and trie
ger response.
Examined Drosera species
Catapult motion in relation to Dionaea
(D. glanduligera = section Coelophylla.
(0.1 to 2 sec.)
All pygmy Drosera = section Bryastrum.)
G = grown from gemmae
(<) slower than (3 to >30 sec.)
(~=) about equal (0. 1 to 1 sec.)
P = perennial plant
(>) faster than (max. 75 ms, recorded in 2012)
S = grown from seeds
(— ) no snap-tentacles
D. androsacea (G)
<
D. callistos (G)
<
D. dichrosepala (P)
—
D. helodes (G)
<
D. echinoblasta (G)
<
D. eneabba (G)
<
D. enodes (P)
—
D. glanduligera (S)
>
D. lasiantha (G)
—
D. leucoblasta (G)
<
D. mannii (G)
<
D. microscapa (G)
~=
D. miniata (G)
<
D. occidentalis (P)
~=
D. platystigma (G)
<
D. pulchella (P)
<
D. pycnoblasta (G)
<
D. pygmaea AUS (P)
~=
D. pygmaea NZL (?)
~=
D. roseana (P)
—
D. scorpioides (P)
—
D. walyunga (G)
<
Remark: Triggered by touching, the initial rapid movement of plants slower than Dionaea
stopped often after approximately 45° to 70°, species moving like Dionaea after about 120° to
140°. They needed further touching to complete the bending. With adding fish food, the bending
was usually complete (~180°), but the speed differed even for identical species; however, was
always the fastest during the first 45°. Due to this behavior and without a high-speed camera, it
was impossible to achieve more precise data for maximum movements.
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Carnivorous Plant Newsletter
with iDS CMOS camera UI146xLE-C. Fi-
ber light source FLQ 150 M with gooseneck
light guide SHF 250.
In contrast to D. glanduligera, fruit flies
are too large as prey for experiments with
the minute snap-tentacles protruding from
leaves with a diameter of only 0.8 to 2 mm.
The test plants in our greenhouse sponta-
neously captured abundant springtails and
several mites that occurred naturally in the
growing media (Figs. 3 & 4). Photos of D.
glanduligera in situ show quite a broad prey
spectrum ranging from springtails and mites
to ants and small centipedes of even larger
size than fruit flies.
Figure 3: An important food source for small
Drosera-. Springtails.
By examining the prey pattern of the
co-occurring D. erythrorhiza, Watson et al.
(1982) established that springtails also play
a very important role at the natural growing
sites. This glue trap with relatively extensive
leaves captured mainly Collembola (76%).
Moreover, this important nutrient source ap-
pears in abundance exactly at the right mo-
ment: when the returning rain opens a new
growing season and the plants awake from Rgure 4 . Drosera ca/fetos captured g
dormancy. Considering 100,000 springtails sprin gtail, which is unab , e to escape using its
in one square meter humid soil to be quite furcula (arrow)
usual, Hopkin (1997) gives a measure of
their relevance for all Drosera with suitable traps.
In addition, Collembola are detritus eaters and like rotting plant debris. Exactly such slowly pu-
trefying leaves are common at the base of many Drosera plants. Even the annual and very fast grow-
ing D. glanduligera develops one new trapping leaf with about 12-18 catapulting tentacles every 3-4
days while the oldest leaves wither correspondingly, becoming a real temptation for detritus eaters.
Attracted in such a manner, they touch the snap-tentacles that lie on the ground like the thread sen-
sors of some spiders and are abruptly lifted onto the sticky leaf center.
We conducted an additional experiment inside our tropical greenhouse (now 18-20°C night,
28-32°C afternoon) to examine the behavior of submerged Drosera traps. Therefore, an 8-cm pot
with green and red D. capensis was placed inside a 3 -liter plastic tank and slowly submerged with
deionized water. We applied two freshly caught houseflies to separate trapping leaves, taking photos
after 15, 30, and 60 minutes to document the curling around the prey underwater, and once within
24 hours during the next four days. As the flies do not stick to submerged tentacles, their legs were
“hooked” into the tentacles and the bodies were once squashed with a forceps to make them im-
mobile as well as to release some body fluid. Both traps folded around the prey in approximately
one hour and remained curled for two to four days, thus indicating that even though submerged, a
certain amount of body fluid reached the traps. However, this is only possible without current in
standing water.
Volume 44 December 2015
175
Tentacle Movement Experiments
Using a zoom-microscope, we comparatively examined the catapult-flypaper trap D. glandulig-
era and 20 species of pygmy Drosera for their tentacle movement. Five species possess only glue-
tentacles and grow erect in their course of development. They are obviously specialized to capture
small flying insects. Their often far protruding marginal tentacles are also able to bend in the range
of several seconds; however, not within fractions of a second (example D. scorpioides). Therefore,
we limited ourselves to the basal rosettes with glue-free snap-tentacles. To trigger the bending we
touched the tentacle heads with a needle.
We carried out the experiments inside a sun-shaded room at a temperature of 22-24°C and ar-
tificial 150 Watt LED workplace lighting. Temporarily, when we needed light that is more intense,
the temperature underneath the microscope could rise up to 30°C. The test plants came directly
from our greenhouse with an afternoon temperature of 20-26°C (see material and methods). As
expected, only a slight touch was necessary to trigger a complete and very fast movement with D.
glanduligera. Its raised tentacle head is unique in the genus (Fig. 5) and works like a foot-switch
(Hartmeyer etal. 2012). Nevertheless, the compressive stressing destroys the hinge-zone; therefore,
each catapult bends only once. In contrast, the snap-tentacles of the pygmy Sundews extend again
within a day and function repeatedly. However, it was more difficult to trigger them; especially the
12 larger species often needed multiple hits. Several tentacles did not react, or an initial bending
stopped after just a short time. Touching the tentacle head only once was apparently not sufficient
for complete bending. With further touching, the movement continues. Presumably, the repeatable
functioning catapults, especially in the larger species examined, need quite a few action potentials
for a complete 1 80°-bending. Triggered by a receptor potential that occurs when the sensitive head
is irritated, such action potentials are electric impulses, which flow through the plant tissue (Fig.
6). In this particular case, triggered in the tentacle head it actuates a hydraulically powered bending
(calculated by Poppinga et al. 2012) of the underneath hinge-zone.
To achieve an uninterrupted bending, we decided to add chemical stimuli together with the me-
chanical. Lichtner et al. (1977) refer to Darwin’s experiments and mention a response to sodium ion,
ammonium ion, and urea. Therefore, we applied minute pieces of crushed fish food flakes (salty pro-
tein with traces of ammonium from decomposition) on the tentacle head. The presence of fish food
turned out to be a smart move: With very few exceptions, all tentacles reacted after some seconds
with a complete bending to the leaf cen-
ter. Obviously, the chemical stimulation
produced a cascade of action potentials
causing a complete bending, unlike sin-
gle mechanical stimulation. However, the
speed of the catapults varied even within
the same species, but now it was possible
to determine the response time between
the application of fish food and the start of
bending relatively exactly. It is 1-2 seconds
for the three smallest and fastest species D.
microscapa, D. occidentalis, D. pygmaea
and 3-12 seconds for the larger ones.
To apply the minute pieces of fish food,
adhering to a needle tip, onto the less than
Figure 5: Drosera glanduligera tentacle
raised head (SEM).
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Carnivorous Plant Newsletter
Figure 6: Measurement of action potentials
on Dionaea lobes in 2009 (a rewarded
experiment by students of the Friedrich-
Konig-Gymnasium in Wurzburg, Germany).
Figure 7: Juvenile springtail sticks to the glue-
free snap-tentacle head of Drosera miniata in
spite of the use of its furcula to escape.
tt T mjfll
v <
V 41
% v \
Figure 8: Drosera enaebba with snap-
tentacles curled by warmness.
100 pm sized tentacle heads under the mi-
croscope turned out to be easier than ex-
pected. Mostly a slight touch was sufficient
and it adhered easily to the mucus-free dry
tentacle head. However, in some cases the
pieces flipped away rapidly, like being re-
pelled. Such a behavior suggests that elec-
trostatic effects may be involved. If the fish
food (crushed inside a plastic lid) had an op-
posite charge, the tentacle head attracted it
and application was easy, while an identical
static charge rejected the pieces. During our
experiments, we could just coincidentally
film a quite small springtail that jumped on a
tentacle head of D. miniata (Fig. 7). The im-
pact was sufficient to trigger the bending and
to lift the prey rapidly from the ground, but
then the movement stopped. The action po-
tentials were probably insufficient for a com-
plete bending because the victim appeared
to be too small. Surprisingly, even now, the
little springtail was not able to release itself
from the tentacle. Circling around the head it
adhered although it desperately used its cata-
pulting furcula to escape (demonstrated on
“Catapults in Pygmyland”). This observation
suggests that electrostatic attraction could
be involved for prey capture with snap-ten-
tacles. Their speed depends strongly on the
condition of the plant and the temperature.
Generally, cool nights and moderate day
temperatures up to 25°C seem to stimulate
a good function. If the temperature is too
high, for instance caused by the lighting dur-
ing the examination, the thin snap-tentacles
tend to curl (Fig. 8) and do not bend any-
more or only very slowly. Unfortunately, we
had no high-speed camera, and the growing
and plant conditions in spring 2015 were not
optimal. In addition, the 13 species propa-
gated from gemmae (see Table 1) were very
young, only about 8-10 weeks old. Bending
caused by touching was mostly not complete
(180°) and when triggered with fish food we
observed varying speed even in the same
species. Therefore, it was impossible to de-
Volume 44 December 2015
177
termine realistic maximum bending speeds of individual species. However, our experiments allow
assessing if a catapult moves faster, in a similar range, or slower than a snap-shutting Dionaea trap
(about 0.1 to 2 seconds). With catapults achieving the amazing speed of 75 milliseconds (Poppinga
et al. 2012) for a 1 80°-movement, so far D. glanduligera remains the fastest and largest catapult-
flypaper trap in the genus. Its high-performance catapults are clearly faster than Dionaea. Speeds
similar to the flytrap, with bending in fractions of a second, are achieved by the catapults of D. mi-
croscapa, D. occidentalis, as well as by the Australian and New Zealand variety of D. pygmaea. The
larger species showed a movement in the range of approximately 3 to more than 30 seconds; these
data are, however, most likely unsuitable to establish maximum speed. D. pulchella for instance often
moved in 10-25 seconds, but once achieved complete movement within approximately 3-4 seconds.
D. enaebba, D. mannii, and D. miniata certainly warrant further experiments as they were not in best
condition. To determine the fastest movement of pygmy catapults correctly will most likely need
observations at their natural habitat. It would be only logical if electrostatic effects between tentacle
head and prey affected the frequency of action potentials and thereby the movement pattern. Many
species grow on silica sand, diatomaceous earth, or between laterite pebbles. Certainly, such soils
charge electrostatically by friction and thereby the soil-dwelling organisms become charged. Silica
sand is quartz, well known for its strong piezoelectric effects generated by friction. However, regard-
ing pygmy Drosera we found no publications on such phenomena so far.
Results and Discussion
The terrestrial and larger Dionaea , which snaps-shut rapidly by a combination of turgor changes
that take place in the trap lobes and an elastic instability, is presumably different from the catapulting
tentacles of D. glanduligera that are small enough to fling prey in fractions of a second solely actu-
ated by hydraulic power (as calculated by Poppinga et al. 2012). Remark: Direct measurements on
the rate of hydraulic actuation (in case that fast tentacle movement relies additional on a release of
elastic energy stored in pre-stressed cells) still have to be undertaken (Poppinga, 2015, pers. comm.).
The features of the catapult-flypaper trap of D. glanduligera encouraged us to keep a closer eye
at the minute tentacles of the considerably smaller pygmy Drosera, focusing at the basal rosettes
with mucus-free snap-tentacles. Their rapidly moving structures are only hard to notice with the
naked eye; therefore, we examined the cultivated plants with a zoom-microscope.
Our experiments show that in contrast to the erect species in section Bryastrum, the acaulescent
species do not bend their laminas during prey trapping. Only tentacles are active, exactly as in the
closely related catapult-flypaper trap of D. glanduligera. Of course, prey-trapping works for all these
species often with mucilage only, in this case the catapults remain inactive. Interestingly both mecha-
nisms flmction independently. Isolated snap-tentacles, which we dissected at the base of the lamina for
high-speed filming in 2012, continued to operate properly without the lamina. The action potentials
affect only the tentacles and have no connection with the lamina in the species reported by Williams
(1976) and very likely these species as well. The tentacles are physically connected just not electri-
cally. Nevertheless, when the catapults are involved, they start a two-stage capture mechanism. The
independently acting glue-tentacles perform the second step, no matter if triggered by the impact of
the flung prey or a direct touching of an insect. They provide the fixation and correct positioning for
digestion like a conveyor belt. This two-stage mechanism is a potential advantage, apparently increas-
ing the availability of nutrients by a larger trapping area in comparison to plants without catapults.
The response time of 8-12 seconds and the 1-2 minutes lasting conveyor belt motion of the
sticky apparatus moved at the same level for all examined species. Only the mucus-free catapults
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Carnivorous Plant Newsletter
were able to respond in 400 milliseconds ( D .
glanduligera ) up to two seconds, and moved
significantly faster. We never found glue-
tentacles that bend in fractions of a second.
Our observations revealed two distinct and
independent acting capture mechanisms in
one trap. One is fundamental, mucilage-
based and relatively slow; the second ap-
pears derived, mucus-free and based on
rapid movement. This is of interest regard-
ing the still remaining big question in the Sundew family (Droseraceae): How could initial passive
or slow flypaper traps develop into mucus-free fast snap-traps?
The surviving stages of trap development are well known. Simple straight glue traps like the phylo-
genetically oldest known Sundews D. regia and D. arcturi , the discussed hydraulic catapults combined
with an initial flypaper lamina and eventually the rapid hydraulically powered mucus-free snap traps
of Aldrovanda and the rapid lobes of Dionaea actuated by a combination of hydraulic movement and
snap-buckling (Poppinga et al. 2013). The thrilling ability of all three Droseraceae genera to capture
prey in fractions of a second, started most likely with the development of broad based marginal ten-
tacles in the plane of the leaf. Different from the erect tentacles on the lamina they are additionally
equipped with a hinge-zone that contains the necessary motor cells to perform the fast movement. Pos-
sibly, they initially still had sticky heads, because all known catapult-flypaper traps still carry a combi-
nation of marginal tentacles with and without mucus producing heads. While the erect glue-tentacles
on the leaf surface are able to move slowly in all directions, marginal tentacles are restricted to bending
up or down due to the broad hinge-zone, but they are very powerful, and rapidly achieve direct hits.
In this respect, it is noteworthy that D. glanduligera and the smallest examined species of section
Bryastrum were able to move two or even almost all catapults nearly synchronically at once (Fig. 9)
like a gripping whole hand. When touching a tentacle more intensely, so that the small leaf totters
just like touched by larger prey, several catapults are triggered almost at once (documented on our
film “Catapults in Pygmyland”). This behavior is certainly effective to capture struggling prey that
is too large for one snap-tentacle only. Simultaneously bending catapults can even be able to fix prey
without any mucilage because they form
first a circular kind of grid cage and act like
securing straps after the described gradual
narrowing (Fig. 10). If rapid enough, they
even capture prey without any glue and push
it onto the sessile digestion glands. That is
an important advantage in areas with heavy
rain, as well as for temporarily submerged
plants. Water washes off the mucilage, so
the sticky part of the trapping mechanism
becomes obsolete. Only the independent
rapid capture mechanism remains active to
supply animal nutrition. Our study shows
that apart from the sessile digestion glands
on the lamina, each single repeatedly cata- Figure 10: Several snap-tentacles acting like
pulting tentacle has all properties known securing straps on Drosera burmannii.
Figure 9: Two catapults of Drosera occidental is
moved synchronically.
Volume 44 December 2015
179
from the trap of the Waterwheel Plant, Aldrovanda. Both are touch-sensitive and able to recognize
chemical stimuli like ammonium ions or sodium chloride (Williams 1976). Both are able to move
initially rapidly as well as gradually for a narrowing by a cascade of action potentials to perform a
cost-benefit calculation, deciding to continue/close or to bend back/reopen. Aldrovanda lobes show
a phase of narrowing after the initial closing: “After the initial rapid closure, the lobes continue
moving through a number of phases. After a period of additional slow closure lasting some 30-60
seconds, in which the outer zones of the two lobes press together completely, the free-side lobe
becomes concave” (Cross 2012, p. 51). Finally, yet importantly, the existence of Aldovanda, the
observations on submerged Dionaea, and our own experiments with submerged D. capensis (see
below) prove clearly that Droseraceae traps function underwater. These facts raise the question: Did
an essential change from flypaper traps to snap traps go through an aquatic stage?
Even temporarily submerged Drosera able to capture prey with a simultaneously rapid snap-
ping of their catapults have to avoid a loss of nutrition by water flow. Therefore, there is a selective
advantage in closing the gaps between the single catapults by merging the bars of the arising grid
formed by the tentacles to achieve a sealed digestion cavity to withhold enzymes and nutrition.
That would at the same time lead to a perfect simultaneous bending of the now connected catapults,
improving the capture of larger prey. Particularly noteworthy in this context is that catapult-flypaper
traps like D. glanduligera possess a pronounced patelliform digestion cavity in the leaf center,
able to contain prey with the volume of 3-4 Drosophila, vanishing totally inside. Our experiments
conducted in 2012 show that the activated overlying tentacles often notably close the opening after
the deposition of prey. Therefore nutrients can be effectively withheld in case of heavy rain or when
temporarily submerged. Our experiments in standing water show that even the leaves of D. capensis
are able to roll in (applied immobile) prey underwater and make use of parts of the nutrients. The
leaves remained curled for 2-4 days before they reopened, indicating that a significant quantity of
nutrients reached the digestion glands even submerged. Optimizing the closure of the existing large
digestion cavity and using the rapid catapults for prey capture would change the former terrestrial or
amphibian catapult-flypaper like trap into an underwater working mucus-free snap-trap with lobes.
It is that way roughly comparable with a primitive Aldrovanda trap. In this perspective, the develop-
ment of straight snap traps from a Drosera- like extinct ancestor of all meanwhile phylogenetically
independent Droseraceae clades, possessing simultaneously rapid bending catapults in temporarily
submerged areas could be a possible and even plausible event. From an evolutionary point of view,
a submerged useless flypaper apparatus became obsolete while the independent acting rapid and
mucus-free capture mechanism prevailed successfully (see Table 2).
We do not speculate that initial snap-traps developed from pygmy Drosera or looked and func-
tioned like A. vesiculosa, which is already highly adapted to straight aquatic conditions. Multifold
aquatic snap traps appeared in the past. The surprisingly found trap of the about six million years old
fossil of the extinct A inopinata differs in parts. It is for instance lacking the trigger hairs (Schlauer
1997). About 20 other meanwhile extinct species of Waterwheel Plants left only seeds or pollen, so
their trap morphology remains unknown. Modem molecular analyses of the chloroplast rbcL gene,
18S rDNA, ORF2280 (Williams et al. 1994; Fay et al. 1997; Lledo et al. 1998; Rivadavia et al.
2003), and the chloroplast matK gene (Meimberg et al. 1999) meanwhile provided widely accepted
phylogenetic trees, which correspondingly show that the snap-traps appeared in the early phylogeny
of the Droseraceae. Surprisingly, these cladograms show a reversal of development, placing the
emergence of Dionaea and Aldrovanda before that of simple flypaper traps like D. regia and D.
arcturi. However, Hosam et al. (2009) state that the estimation of genetic distances based on six
chloroplast intergenic regions led to the conclusion that the chloroplast genome of A. vesiculosa
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Table 2.
Cladogram based on the most parsmonious tree resulting from parsimony
analysis of the combined rbcL and 18S rDNA sequences by Rivadavia etal.
(2002), supplemented by S. Hartmeyer (2015).
— Drosera anglica
— D. montana var. tomentosa
— D. sessilifolia
- D. platypoda
- D. pygmaea
- D. glanduligera
t \
D. arcturi p ' #
k l
D. regia *
'Mk 1
Dionaea muscipula | B
— Aldrovanda vesiculosa
Drosophyllum lusitanicum
Nepenthes alata
Simmondsia chinensis (no traps)
Immobile Immobile Slow Moderate Rapid Snap trap
pitfall trap flypaper flypaper catapult catapult (< 1 sec.)
(minutes) (> 2 sec.) (< Isec.)
Volume 44 December 2015
181
matches more closely to that of Drosera regia than its sister genus Dionaea. They suspect that the
inconsistency between genetic distance estimates based on nuclear and cytoplasmic markers may
reflect a chloroplast capture (e.g., by hybridization) because his result is inconsistent with Rivadavia
et al. (2003) who conclude that the sister relationship of Aldrovanda and Dionaea indicates a single
evolutionary origin of the snap trap system in plants. Nevertheless, Rivadavia states that it was not
possible to elucidate which trap system the common ancestor of these lineages had or whether the
two systems evolved independently from non-carnivorous plants. Phylogenetic analyses alone pro-
vide without doubt acknowledged cladograms; they are, however, not sufficient to establish the cor-
rect position of single organisms unambiguously, especially if they are closely related and have only
few mutations in the analyzed genes, just like in the case of Dionaea and the particular relation of
Aldrovanda with Drosera. A confirmation of the determined position inside the phylogenetic tree by
other methods like physiological, morphological, and functional characteristics is necessary. There-
fore, the existing cladograms do not definitely clarify whether the aquatic snap trap, the terrestrial
snap trap, and the catapult-flypaper traps, all assigned to separate clades, developed independently
from one another or not. Considering that, the hypothesis based on our experiments that the aquatic
snap trap could have arisen from submerged simultaneously snapping catapult-flypaper-like traps in
the early Tertiary or even in the late Cretaceous, can still be considered possible.
Our experiments prove first the existence of several Drosera species with rapidly moving catapults,
which appear on all cladograms among the phylogenetically oldest Sundews (D. glanduligera and D.
pygmaea) following the simple glue traps D. regia and D. arcturi (most parsimonious tree, Rivadavia
et al. 2003). It is evident that each catapult shows the same hydraulically powered movement, identi-
cal tactile and chemical sensitivity and even a similar narrowing behavior that occur in Aldrovanda
and Dionaea. Therefore, the current cladogram induced impression of an independent convergent
evolution of the three Droseraceae genera from an unknown initial flypaper trap appears in a relative
perspective. All Droseraceae genera possess a fast moving apparatus; rapid snapping is not a unique
function of snap traps. Nevertheless, the development of rapid catapults from slow mucus-tentacles
in Drosera is obvious. Drosera is the type genus of its family, and it has all structures present in
the stalked glands of any of the other members (Williams 1976). A scenario that initial and slow
flypaper traps like D. regia or D. arcturi emerged from Aldrovanda or Dionaea related snap traps is
very unlikely. Considering this, we miss a common ancestor in the early Tertiary or late Cretaceous
connecting the initial flypaper Sundews with the rapid catapulting Drosera. In this regard, the unique
ontogeny of the D. glanduligera catapults provides an inside view how evolution acts. Other than the
seedlings of more derived Drosera species that possess mucus-free snap-tentacles directly after the
cotyledons, D. glanduligera starts with marginal glue-tentacles. Within about 4-6 weeks, the consecu-
tive new leaves show through intermediate forms an ongoing development until functioning mucus-
free catapults result (Hartmeyer & Hartmeyer 2010). That indicates an ancestor with straight flypaper
traps in the early Tertiary or late Cretaceous. Unfortunately, it is impossible to complete the existing
phylogenetic trees by adding that unknown initial DNA. However, assumed as unknown ancestor
for the carnivorous genera in Drosophyllaceae, Dioncophyllaceae, and Nepenthaceae, which divided
earlier on the cladograms is a plant that most likely had flypaper traps. It is certainly related with the
Droseraceae, as all these genera are members of the order Caryophyllales (Meimberg et al. 2000).
Another Possible Area for Future Experiments
Our study shows that the importance of function and interplay of tentacles, in particular Drosera
traps, is still underestimated and demands further examination. Through our experiments we could
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prove that pygmy Drosera possess rapid catapult-flypaper traps, but there may be even more species in
the genus and highly likely in section Bryastrum. To look out for more rapid traps is one field for future
experiments, as there are still species with prominent snap-tentacles waiting for a closer inspection
from a functional morphological point of view. In addition, the question why fish food and springtails
adhere to the mucus-free dry tentacle heads is worth further examination. The receptor and action
potentials that trigger the rapid movements result mainly from Ca" -ions stored in the tentacle heads
and lobes, thus turning those structures into a kind of electrode. How important are electrostatic effects
for prey capture? What role do charged soils like silica sand play? That requires eventually a detailed
observation of the traps in their natural environment. Another attempt could be to find the responsible
genes for the rapid hydraulic movements for a comparative analysis of all rapidly moving Droseraceae
traps. Their phylogeny still raises a number of questions, which demand further experiments.
Acknowledgement: The authors would like to thank Dr. Jan Schlauer for providing important literature
as well as Andy Landgraf for his kind permission to include some of his excellent macro photos to
our accompanying documentary film on YouTube (Catapults in Pygmyland). Furthermore, we thank
Gideon Lim who provided his first video shots on catapulting tentacles of the all green New Zealand
variety of D. pygmaea. Special thanks for their detailed reviews go to Prof. Stephen E. Williams, who
waived anonymity, and one anonymous reviewer. Both helped a lot to improve this article. Finally, yet
importantly, we thank Richard (Tilbrooke) Davion, who first reported about catapulting action in the
genus Drosera , for his in situ photos from South Australia to identify different prey on D. glanduligera.
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Cross, A. 2012. Aldrovanda. Redfern Natural History Productions. Poole, Dorset, England.
Darwin, C. 1875. Insectivorous Plants. London: John Murray.
Elansary, H.O.M., Adamec, L., and Storchova, H. 2010. Uniformity of organellar DNA m Aldrovan-
da vesiculosa, an endangered aquatic carnivorous species, distributed across four continents.
Aquatic Bot. 92: 214-220.
Fay, M.F., Cameron, K.M., Prance, G.T., Lledo, M.D., and Chase, M.W. 1997. Familial relationships
of Rhabdodendron (Rhabdodendraceae). Plastid rbcL sequences indicate a caryophyllid place-
ment. Kew Bulletin 52 (4): 923-932.
Gibson, T.C., and Waller, D.M. 2009. Evolving Darwin’s most wonderful plant: ecological steps
to a snap-trap. New Phytol. 2009; 183: 575-87; PMID:19573135; http:/dx.doi.org/10.1 1 1 1/j.
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Hartmeyer, I., and Hartmeyer, S.R.H. 2005. Drosera glanduligera - Der Sonnentau mit “Klapp-
Tentakeln”. Das Taublatt 2005/2: 34-38.
Hartmeyer, I., and Hartmeyer, S.R.H. 2010. Snap-tentacles and runway lights. Carniv. PI. Newslett.
39: 101-113.
Hartmeyer, I., Hartmeyer, S.R.H., Masselter, T., Seidel, R., Speck, T., and Poppinga, S. 2013. Cata-
pults into a deadly trap: The unique prey-capture mechanism of Drosera glanduligera. Carniv.
PI. Newslett. 42: 4-14.
Hartmeyer, S.R.H., and Hartmeyer, I. (2015). Catapults in Pygmyland. Accompanying documentary
film on YouTube: https://www. youtube. com/watch?v=5k7GYGibdjM.
Heubl, G., Bringmann, G. and Meimberg, H. 2006. Molecular phylogeny and character evolution of
carnivorous plant families in Caryophyllales - Revisited. PI. Biol. 8: 821-830.
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Hopkin, S.P. 1997. Biology of the Springtails (Insecta: Collembola). Oxford: Oxford University Press.
Juniper, B.E., Robins, R.J., and Joel, D.M. 1989. The Carnivorous Plants. Academic Press, London.
Lichtner, F.T., and Williams, S.E. 1977. Prey capture and factors controlling trap narrowing in Dio-
naea (Droseraceae). Amer. J. Bot. 64: 881-886.
Lledo, M.D., Crespo, M.B., Cameron, K.M., Fay, M.F., and Chase, M.W. 1998 Systematics of Plum-
baginaceae based upon analysis of rbcL sequence data. Syst. Bot. 23(1): 21-29.
Lowrie, A. 2013. Carnivorous Plants of Australia Magnum Opus Vol. 1-3. Redfern Natural History
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McPherson, S. 2008. Glistening Carnivores - The Sticky-Leaved Insect-Eating Plants. Redfern Nat-
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Meimberg, H., Dittrich, P, Bringmann, G., Schlauer, J., and Heubl, G. 2000. Molecular phylogeny
of Caryophyllidae s.l. based on MatK sequences with special emphasis on carnivorous taxa. PI.
Biol. 2(2): 218-228.
Nakamura, Y., Reichelt, M., Mayer, VE., and Mithofer, A. 2013. Jasmonates trigger prey-induced
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pulting tentacles in a sticky carnivorous plant. PLoS ONE; 7:e45735; PMID:23049849; http://
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Technical Refereed Contribution
Soil pH values at sites of terrestrial carnivorous plants
IN SOUTH-WEST EUROPE
Lubomir Adamec • Institute of Botany of the Czech Academy of Sciences • Dukelska 135 • CZ-379
82 Trebon • Czech Republic • lubomir.adamec@ibot.cas.cz
Keywords: Soil water pH, neutral soils, Pinguicula spp., Drosera intermedia, Drosophyllum
lusitanicum.
Abstract: Although the majority of terrestrial carnivorous plants grow in acidic soils at a pH of 3. 5-5. 5, there are
many dozens of carnivorous species, mostly mountainous or rocky Pinguicula species, which grow preferen-
tially or strictly in neutral or slightly alkaline soils at pHs between 7-8. Knowledge of an optimum soil pH value
and an amplitude of this factor may be important not only for understanding the ecology of various species and
their conservation, but also for successfully growmg them. I report soil pH values at microsites of 15 terrestrial
carnivorous plant species or subspecies in SW Europe.
Introduction
The majority of terrestrial carnivorous plants grow in wetlands such as peat bogs, fens, wet meadows, or wet
clayish sands. The soils have usually low available mineral nutrient content (N, P, K, Ca, Mg), are hypoxic or
anoxic and usually acidic (Juniper et al. 1989; Adamec 1997; Rice 2006). Unlike mineral nutritional character-
istics of these soils, which have commonly been studied and related to carnivorous plant growth in the field or
greenhouse experiments and which have also been published (for the review see Adamec 1997), relatively very
little is known about the relationship between soil pH and growth of terrestrial carnivorous plants. Although some
limited knowledge of soil pH at habitats of carnivorous plants or in typical substrates exist among botanists and
growers (e.g., Roberts & Oosting 1958; Aldenius et al. 1983; Studnicka 1989; Correia & Freitas 2002; Garrido et
al. 2003; Adlassnig et al. 2006; Rice 2006; Adamec 2009), these items of knowledge are not comprehensive and
available for each species and are rather scattered. Even when new carnivorous plant species are described, the pH
value of the soil in which they grow is usually not reported (e.g., Casper 2004).
pH value in the soil rooting medium is one of the most important soil factors, comparable with the available
contents of macronutrients (Marschner 1995). On the one hand, soil pH tells about the availability of cation ex-
change of soil particles for H + and, on the other hand, it characterizes the ability of uptake of metallic cations from
the soil by antiport uptake mechanisms (e.g., K7H + ). Moreover, the low soil pH known for the majority of terres-
trial carnivorous plant habitats in combination with wet soils (or waterlogging) - i.e., hypoxia or anoxia and low re-
dox potential - can cause both deficiency of some microelements (Mo) and toxicity of others (Fe 2+ , Al 3+ ; Aldenius
et al. 1983; Adamec 1 997). In contrast, unusually high soil pH associated with high Ca 2+ and Mg 2+ soil contents can
lead to soil phosphate precipitation and P deficiency of plants (Marschner 1995). In Drosera rotundifolia grown
in a diluted mineral nutrient solution differing in pH, Rychnovska-Soudkova (1954) showed a principal growth
effect of different pH according to the mineral N forms available. Thus, though pH value of wet soils appears to be
important for growth of carnivorous plants, only a few manipulative soil pH experiments have been conducted on
carnivorous plants so far (Adamec et al. 1992; Adamec 1996). Results of these layman greenhouse growth studies,
in which a natural peaty substrate was alkalized or acidified by ca. one pH unit using NaHC0 3 or HC1, are rather
ambiguous but show that certain species may react - positively or negatively - on changes of soil pH.
Volume 44 December 2015
185
The majority of terrestrial carnivorous plants grow in acidic soils, but the exact natural soil pH values or the
pH amplitudes are known only for several species (e.g., Roberts & Oosting 1958; Aldenius et al. 1983; Studnicka
1989; Adamec 1996, 2009; Correia & Freitas 2002; Garrido et al. 2003; Adlassnig et al. 2006). However, within
the Pingiiicula genus, there are several dozens of species growing in neutral or slightly alkaline limestone or do-
lomitic soils mostly in mountains with their habitats in wet, dripping or sprayed rocks (Rice 2006). They mainly
occur in SW and S Europe and Mexico. It is known that some eurytopic, widely spread carnivorous species tolerate
rather wide amplitude of soil pH values. E.g., Drosera rotundifolia in the Czech Republic was found to grow at
pH between 2. 9-6. 5 (Adamec 1996) and Pingiiicula vulgaris in N Sweden was reported to grow at pH values of
4. 1-6.7 (Aldenius et al. 1983); the true pH amplitude can be much wider. On the other hand, an immensely rare
Czech endemic lowland species Pingiiicula bohemica, which is very similar to the former species with which it
can co-occur, is stenotopic and only grows within a very narrow range of pH between 6.2-6. 9 in base-rich fens
(Studnicka 1989). It is anticipated that European mountainous Pinguicula species occurring on wet limestone or
dolomitic rocks (e.g., P. grancli flora, P. vallisneriifolia, P. poldinii ) shall grow in alkaline or at least neutral soils.
In line, the only pH soil measurement available for P. crystallina from SE Turkey shows soil pH of 7.5 (Adamec
& Pasek 2000). In this study, I show soil pH values at microsites of 15 terrestrial carnivorous plant species or
subspecies in SW Europe.
Methods
Dozens of sites of terrestrial carnivorous plants of the Pinguicula genus, Drosera intermedia, and Dro-
sophyllum lusitanicum were visited during a trip of Czech carnivorous plant growers to SW France, Spain,
Portugal, and NW Italy during 26 April - 6 May 2005. As some plant populations did not flower, exact species
determination was not possible. Otherwise, the determination was also partly based on pieces of exact informa-
tion on the distribution of some species (or hybrids) provided by local experts. Exact site names are omitted here
for the reason of plant protection. Mixed soil samples were collected using a pair of forceps very close to the
root system at each microsite and placed into plastic vials. Usually from 3-5 subsamples from different adjacent
plant colonies, ca. 6-12 g of wet mass of a mixed sample was collected at each site. Water pH of the collected
soil samples was measured in a laboratory by a pH electrode in soil suspensions (soilrwater ca. 1 :2 v/v; 5 h).
Median and range of values are shown (Table 1). When needed, median was calculated through H + concentra-
tions. For comparison, published soil pH data on Drosophyllum lusitanicum from Spain and Portugal (Adamec
2009) are also presented.
Results and Discussion
The species studied can be subdivided by their soil pH values into two distinct categories (Table 1).
One category, represented by P. lusitanica, Drosera intermedia, and Drosophyllum lusitanicum, can be
called as “acidophilous”. These species clearly prefer acidic soils (medians 4. 2-5. 8), their soil pH ampli-
tudes are rather wide (usually >2 pH units; see also Adamec 1996, 2009), and the upper pH ranges reach
medium values of ca. 6. 5-7.0. D. lusitanicum is a typical example as its total pH range known from the
literature is 3. 6-7.0 (see Adamec 2009). At several visited sites, D. lusitanicum grew at dry, rocky, or
stony microsites very close (commonly only 20-30 m) to wet P. lusitanica microsites (especially along
roads) and, thus, the pH values based on the same substrate were similar. Other typical members of this
category are Drosera rotundifolia growing at pH between 2. 9-6. 5 (Adamec 1996) and P. vulgaris between
at least 4. 1-6.7 (Aldenius et al. 1983). As these “acidophilous” species usually do not extend to pH of 7.0,
they probably cannot grow in slightly alkaline soils. Soil pH values usually correlate with the content of
available Ca 2+ plus Mg 2+ and, thus, it is accepted that the growth of these “calcifuge” species at medium or
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Carnivorous Plant Newsletter
Table 1. pH values of mixed soil samples from microsites in SW and S Europe. ?, un-
certain determination of the plants, n, number of microsites. *, data taken from Adamec
(2009).
Species
n
Median
Range
P. grandiflora
2
7.27
7.04-7.78
P. grandiflora subsp. rosea
1
8.04
—
P. grandiflora x P. vulgaris ?
1
5.69
—
P grandiflora x R longifolia ?
2
7.23
7.11-7.40
P dertosensis ?
2
7.20
6.91-8.74
P mundii
2
7.66
7.54-7.83
P. vallisneriifolia
3
7.74
7.49-7.78
P longifolia subsp. causensis
2
7.35
7.08-8.27
P. longifolia subsp. longifolia
2
7.17
7.04-7.36
P. longifolia subsp. reichenbachiana
5
7.55
6.90-7.89
P crystallina subsp. hirtiflora
1
6.90
—
P. poldinii
1
7.51
—
P. lusitanica
7
5.84
4.21-6.57
Drosera intermedia
3
4.21
3.79-5.05
Drosophyllum lusitanicum*
10
4.40
3.67-5.30
higher pH values is rather inhibited by these divalent cations than by pH in itself (Rychnovska-Soudkova
1953; Juniper et al. 1989).
On the other hand, all the other Pinguicula species or their hybrids (but P. grandiflorci x P vulgaris ?) in-
vestigated can be considered “neutrophilous” and/or “alkalophilous” (Table 1). The typical soil pH values are
within 7. 0-8.0. Theoretically, as a water suspension of milled pure limestone or dolomite should have pH >8.5,
the commonly measured lower values prove that the alkaline soil bedrock in the rooting medium was neutralized
and acidified by soil organic matter and root exudates. Similarly as in the case of the “acidophilous” species, the
pH amplitude was wide 1-2 pH units and could be caused by different proportion of organic matter in the soils
which usually occurred on vertical limestone rocks. Moreover, these soils on vertical rocks were mostly only
10-15 mm deep. The results show that “neutrophilous” Pinguicula species grow in soils the pH of which never
decreases below 6.9. The putative hybrid P. grandiflora x P. vulgaris indicates that the exceptionally low soil pH
(5.7) for “neutrophilous” Pinguicula species was influenced by the “acidophilous” parental species P. vulgaris.
The results shown in Table 1 should be taken into account when preparing suitable peaty substrates for differ-
ent plant groups. While “acidophilous” species grow well in acidic, base-poor peaty substrates at pH of 4.0±0.5,
the “neutrophilous” species need an addition of ca. 5-10 % (v/v) milled or ground limestone for alkalization of
the acidic peat to the pH of >7.0 (Rice 2006).
Acknowledgements: This study was funded partly by the Research Programme of the Czech Academy of Sci-
ences (No. RVO 67985939). The author is grateful to Drs. Begona Garrido, Arndt Hampe, and Mr. Mario Valente
for guiding through natural sites. Thanks are also due to my trip colleagues Drs. Romana Rybkova, Vlastik
Rybka, Jaroslav Liska, and Jan Flisek for organizing this trip and plant determination. Special thanks are due to
Prof. Jiirg Steiger for providing us with information on local Pinguicula sites.
Volume 44 December 2015
187
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performance of the threatened insectivorous plant Drosophyllum lusitanicum (Droseraceae). Divers. Distrib.
9: 335-350.
Juniper, B.E., Robins, R.J., and Joel, D.M. 1989. The Carnivorous Plants. Academic Press, London.
Marschner, H. 1995. Mineral Nutrition of Higher Plants. Academic Press, London.
Rice, B.A. 2006. Growing Carnivorous Plants. Timber Press, Portland, USA.
Roberts, P.R., and Oosting, H.J. 1958. Responses of Venus fly trap ( Dionaea muscipula) to factors involved in
its endemism. Ecol. Monographs 28: 193-218.
Rychnovska-Soudkova, M. 1953. (Study on mineral nutrition of Drosera rotundifolia L. I. Influence of calcium
as an important physiological and ecological factor.) In Czech. Preslia (Prague) 25: 51-66.
Rychnovska-Soudkova, M. 1954. (Study on mineral nutrition of Drosera rotundifolia L. II. Root sorption of
inorganic nitrogen.) In Czech. Preslia (Prague) 26: 55-66.
Studnicka, M. 1989. (Czech butterwort: a study of a critically endangered Pinguicula bohemica species as regards
to a possibility of its conservation.) In Czech. PhD-thesis, Institute of Botany, Pruhonice, Czechoslovakia.
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188
Carnivorous Plant Newsletter
Technical Refereed Contribution
IS LONG-TERM SURVIVAL OF DRIED TURIONS OF
AQUATIC CARNIVOROUS PLANTS POSSIBLE?
Lubomir Adamec • Institute of Botany of the Czech Academy of Sciences • Dukelska 135 • CZ-379
82 Tfebon • Czech Republic • lubomir.adamec@ibot.cas.cz
Keywords: Aldrovanda vesiculosa, Utricularia spp., winter buds, turion drying and freezing, turion
sprouting.
Introduction
Turions of perennial aquatic carnivorous plants of the genera Aldrovanda and Utricularia are
dormant, overwintering buds and are formed by extreme condensation of short, modified leaves in
the shoot apex at the end of the growing season (Fig. 1) (Sculthorpe 1967; Bartley & Spence 1987;
Adamec 1999). These tough organs represent also storage organs both for carbohydrates and some
mineral nutrients (N, P; Winston & Gorham 1979a; Adamec 1999, 2003, 2010, 201 1; Plachno et al.
2014) and their respiration rate is greatly reduced as compared to that of summer shoots (Adamec
2003, 2008a, 2011). Turions are partly frost-resistant organs which usually overwinter in shallow
waters close to the bottom and escape from being included in ice (Adamec 1999). In some species
and very shallow habitats, however, turions overwinter also above the water surface in the terrestrial
ecophase, on wet organic substrate. Thus, these turions can face both freezing and drying in these
microhabitats. Adamec & Kucerova (2013) investigated the characteristics of frost-resistance of
turions of 8 aquatic carnivorous plant species and measured the freezing temperature of autumnal,
dormant, non-hardened turions (interpreted as freezing of extracellular water) within a range of -7.0
to -10.2°C, whereas the freezing temperature of outdoor hardened turions of 6 species was within
a very narrow range of -2.8 to -3.3 °C. These characteristics suggest that turions can be hardened
by weak frosts and that their hardiness is based on the shift from frost avoidance in non-hardened
autumnal turions to frost tolerance in the spring.
Data are available that turions of several Utricularia species are able to survive drying and
sprout. Maier (1973 a) found that U vulgaris turions dried for 1-123 days were able to sprout and
grow. However, the older the turions were, the less tolerant of drying they were. Turions refrigerated
for five months before being dried out survived very poorly. Turions of U. vulgaris, U. australis, U.
intermedia, and U. minor were able to withstand drying out (24±3°C, 33% RH) for 5-19 days and,
in addition, the drying markedly shortened innate turion dormancy: from 12-48 days in control
turions to only 5-7 days in dried ones (Maier 1973b). In another study, Adamec (2008b) found that
the survival of spring dried turions was distinctly species-specific: U. australis and U. ochroleuca s.
str. completely survived drying at 3°C for 5 days, but U. bremii and Aldrovanda vesiculosa did not.
U. australis showed to be very resistant to drying and survived at 89-100% even a long dry period
of 375 days, but U. ochroleuca did not at all. Moreover, dried U. australis turions even survived (at
100%) freezing at -11°C for 5 days indicating a possibility for a long-term turion survival in dry
state. As turions lose major part of their storage carbohydrates over winter (Winston & Gorham
1979a; Adamec 1999, 2003, 2008a), under natural conditions (and also in a refrigerator), they can
survive only from one season to another (Adamec 1999, 2003). On the physiological level, the
Volume 44 December 2015
189
Aldrovanda vesiculosa
Utricularia stygia
Utricularia vulgaris
Utricularia macrorhiza
Utricularia bremii
Figure 1: Ripe or just sprouting turions of Aldrovanda vesiculosa , Utricularia stygia, U.
vulgaris, U. macrorhiza, and U. bremii.
190
Carnivorous Plant Newsletter
overwintering and stages of dormancy in U. vulgaris turions are regulated by native phytohormones,
mainly by the ratio of activities of abscisic and gibberellic acid (Winston & Gorham 1979b).
The aim of this paper was to investigate survival of turions of 6 aquatic carnivorous plant spe-
cies after long periods of drought in a combination with frost, to test a possibility to prolong the
relatively short turion life-span when stored in water in a refrigerator. A protective effect of paraffin
oil on turion storage was also tested.
Materials and Methods
Ripe dormant turions of Utricularia australis (collected from two different sites from Trebon
basin, S Bohemia, Czech Rep.: humic pool at Ptaci blato and at Pihulik), U. intermedia and U. stygia
(formerly U. ochroleuca s. lato; both species from Trebon basin), and U. bremii (from Lake Oniega,
NW Russia; the latter three species freshly collected from the outdoor collection of the Institute of
Botany at Trebon) were thoroughly washed by tap water, blotted dry, put on an open Petri dish, and
let dry out in a refrigerator at 3±1 °C and 59±2% RH for 4 days. On 3 Nov. 2006, dozens of dried tu-
rions were put in plastic vials and kept either frozen at - 12±1 °C, refrigerated at 3±1 °C or in darkness
at room temperature of 20 to 26°C for 17 months (517 days). After this treatment, 15-20 turions of
each variant were put in filtered humic culture water in a miniphytotron at 20±1°C in white fluores-
cent light (ca. 180 pmol nr 2 s' 1 ; 12/12 h L/D) for 26 days to test their survival and sprouting ability.
As the turion sprouting of some species was very low indicating that the innate dormancy might
not be broken sufficiently by the drying (sensu Maier 1973b), turions in the culture water were then
put to a refrigerator at 3±1°C for 2 months to break their innate dormancy. After this cold treat-
ment, turions were allowed to sprout in the miniphytotron at 20±1°C in light for another 30 days.
Non-sprouting but still living turions were then transferred outdoors and the vials with turions were
let floating on the surface of an outdoor growth container in full sun at ca. 20-30°C for two days.
Twenty parallel dried U. australis turions (from Pihulik pool) were kept frozen at -12±1°C for 29
months (882 days), then put in the culture water at 3±1°C for 3 1 days to break the innate dormancy,
and were then allowed to sprout in the miniphytotron at 20±1°C in light. Another 20 parallel dried
U. australis turions were kept in darkness at 20 to 26°C for 64 months (1936 days) and were then
allowed to sprout at 20±1°C in light.
In another experiment on 2 Nov. 2011, 10-20 freshly collected dormant turions of each of A.
vesiculosa (from SW Hungary, collected from Suchdol nad Luznici sand-pit), U. australis and U.
bremii (both latter species taken from the collection) were thoroughly blotted dry, put in a small
plastic vial with liquid paraffin oil, and kept refrigerated at 2±1°C for 68-81 days to learn whether
this water-free medium can facilitate turion survival at low temperature. They were then blotted dry,
put in the culture water and allowed to sprout in the miniphytotron at 20±1°C in light. In another ex-
periment on 1 1 Dec. 2011, 10 dormant turions of each of A. vesiculosa (from E Poland), U. australis
and U. ochroleuca s. str. (from Trebon basin; all species taken from the collection) were thoroughly
blotted dry, put in a small plastic vial with paraffin oil, and kept frozen at - 1 4± 1 °C for 72 days. Then,
turion sprouting was tested in the culture water at 20±1°C in light.
Turions of all species were scored as sprouting if they distinctly reflexed their basal leaf whorls
and partly opened themselves (see Adamec 2003, 2008), and as dead if they were blackened without
any sign of sprouting. Although the sprouting of control turions, which were kept standardly in the
culture water at 3±1°C in darkness, was not estimated within the above experiments, it is well-
known from other experiments and tests (e.g., Adamec 2003, 2008b; Adamec & Kucerova 2013)
that the percentage of sprouting at 20°C in light in each species was nearly 100%.
Volume 44 December 2015
191
Results and Discussion
Similarly as in the previous study (Adamec 2008b), turions of U. australis showed to be the most
resistant to long-term drying of all species investigated (Table 1). Dried dormant U. australis turions
were able to survive both freezing at -12°C and keeping at 3°C for 17 months and fully sprouted
afterwards only after additionally breaking the innate dormancy by a next 2-month cold treatment
and after exposing to bright light. Thus, as opposed to results of Maier (1973b), who dried and
stored turions of 4 Utricularia species at a relatively high temperature (24±3°C, 33% RH) for 5-19
days, U. australis turions dried at 3± 1 °C in this study did not break their dormancy at all. However,
a weak breaking of dormancy was found in turions of U. bremii and U. stygia frozen at - 12°C. Dried
U. australis turions could only survive when kept frozen or at 3°C for 17 months, but not at room
temperature. In line, parallel dried U. australis turions kept at room temperature for 64 months died
during rehydration (data not shown). Dried U. intermedia turions did not survive the rehydration
after both treatments and, except for frozen U. bremii turions, the same also applied for turions of
U. bremii and U. stygia (Table 1). Although dried U. australis turions were able to fully survive
freezing at -12°C for 17 months, they completely died after 29 months of the same treatment during
rehydration (data not shown). Thus, a marked species-specificity was found for long-term survival
of dried turions at low temperatures.
Table 1. Sprouting of dried Utricularia turions originating from outdoor collection but U.
australis \ collected from Ptacf blato pool, and U. australis 2 , collected from Pihulik pool.
First, dormant autumnal turions were dried in a refrigerator at 3°C for 4 days. As a treat-
ment, they were kept dry at -12°C, 3°C, or 20 to 26°C for 17 months. Afterwards, they
were put in culture water and allowed to sprout in light at 20°C in a thermostat chamber
for 26 d. Then, non-sprouting turions were kept in the water in a refrigerator at 3°C and
darkness to break dormancy for next 2 months and allowed to sprout in light at 20°C for
30 d again (sprouting scored after 10 and 30 d). The remaining turions were then trans-
ferred outdoors where they could sprout in natural light, (dead), all remaining turions
were blackened and dead.
Species
Number
of
turions
Treatment
of dry
turions for
17 months
Cumulative number of sprouting turions
At 20°C
after 26 d
After next 2-month cold
treatment at 3°C; in
light at 20°C after next
Outdoors
full sun
(after 2 d)
10 d
30 d
U. australis 1
20
-12°C
0
2
4
20
u
20
3°C
0
8
11
20
U. australis 2
20
20 to 26°C
0 (dead)
—
—
—
U. intermedia
15
-12°C
0 (dead)
—
—
—
15
3°C
0 (dead)
—
—
—
U. bremii
20
-12°C
5
0
0
0 (dead)
u
20
3°C
0 (dead)
—
—
—
U. stygia
20
-12°C
3 (dead)
—
—
—
u
20
3°C
1 (dead)
-
-
-
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Carnivorous Plant Newsletter
Dormant humid turions of three species (A. vesiculosa, U. bremii , U. ochroleuca) survived being
immersed in paraffin oil at 2°C for 68-81 days and sprouted then at 83-100% - comparably with
controls (data not shown). Similarly, non-dormant turions of the three species kept under these con-
ditions in paraffin oil for 4 months sprouted at 90-100% (data not shown). However, after dormant
humid turions of three species (A. vesiculosa, U. australis, U. ochroleuca) had been kept frozen at
-14°C for 72 days, all turions died during rehydration (data not shown). Thus, keeping of blotted-dry
turions in paraffin oil in a refrigerator at temperatures above zero or in a frozen state does not render
any advantage for turion overwintering and cannot be recommended, though the effect of paraffin
oil in itself is harmless.
As found recently (Adamec & Kucerova 2013), dormant, non-hardened wet turions of 8 aquat-
ic carnivorous species froze within a range of -7.0 to -10.2°C and freezing was usually lethal for
the turions. Out of all tested species in the present and previous study (Adamec 2008b), the turions
of U. australis were clearly the most resistant both to drying and freezing of dried turions. Yet, the
freezing temperature of both non-hardened (-9.0±0.3°C) and hardened turions (-3.1±0.1°C) of U.
australis lay near the means for all species and did not indicate at all an exceptionally high frost
resistance (Adamec & Kucerova 2013). In line, it is not clear which endogenous factor cause U.
australis turions to be rather tolerant to long-term drying. Though this species grows also in very
shallow habitats and can even survive longer periods of growing in the (semi)terrestrial ecophase
on wet substrate (Adamec 2008b), another 4 relative species investigated ( U. bremii, U. interme-
dia, U. ochroleuca, U. stygia ) normally grow also in the terrestrial ecophase on wet substrate and
their turions should be adapted better to occasional drying out and freezing over winter - but they
are not.
In conclusion, turions of aquatic carnivorous plants have evolved to survive only a limited, ca.
half-year period of unfavorable frosty or cold conditions, i.e., from one season to the next. There-
fore, due to their metabolism, their life-span even under ecological, cold overwintering conditions
is usually limited to ca. a half year (Adamec 2008a, b). Turions of some resistant species are able to
withstand drying at low or room temperature and subsequent keeping in cold even for one year and
normally sprout afterwards. Yet, drying of dormant, autumnal turions may not be followed by break-
ing the innate dormancy (Table 1), while drying of non-dormant, spring turions having been kept at
above zero temperatures in a refrigerator may be harmless (Maier 1973b). As shown in this study, a
long-term keeping of dormant dried turions either at a low temperature (ca. 2 to 3°C) or frozen at ca.
-12°C is not possible (except for common U. australis). Thus, a long-term keeping of dried turions
of aquatic carnivorous plants at any temperature is not possible and cannot be recommended. A stor-
age using a paraffin oil cannot be recommended, either. The best way to overwinter the turions is to
keep them at a very low, above zero temperature (1 to 2°C) under water or in a wet state.
Acknowledgements: This study was funded partly by the Research Programme of the Czech Acad-
emy of Sciences (No. RVO 67985939).
References
Adamec, L. 1999. Turion overwintering of aquatic carnivorous plants. Camiv. PI. Newslett. 28:
19-24.
Adamec, L. 2003. Ecophysiological characterization of dormancy states in turions of the aquatic
carnivorous plant Aldrovanda vesiculosa. Biol. Plant. 47: 395-402.
Adamec, L. 2008a. Respiration of turions and winter apices in aquatic carnivorous plants. Biologia
63: 515-520.
Volume 44 December 2015
193
Adamec, L. 2008b. Survival of dried turions of aquatic carnivorous plants. Carniv. PI. Newslett. 37:
52-56.
Adamec, L. 2010. Tissue mineral nutrient content in turions of aquatic plants: does it represent a
storage function? Fundam. Appl. Limnol. 176: 145-151.
Adamec, L. 201 1. Dark respiration and photosynthesis of dormant and sprouting turions of aquatic
plants. Fundam. Appl. Limnol. 179: 151-158.
Adamec, L., and Kucerova, A. 2013. Overwintering temperatures affect freezing temperatures of
turions of aquatic plants. Flora 208: 497-501.
Bartley, M.R., and Spence, D.H.N. 1987. Dormancy and propagation in helophytes and hydro-
phytes. Arch. Hydrobiol. (Beih.) 27: 139-155.
Maier, R. 1973a. Das Austreiben der Turionen von Utricularia vulgaris L. nach verschiedenen lan-
gen Perioden der Austrocknung. Flora 162: 269-283.
Maier, R. 1973b. Wirkung von Trockenheit auf den Austrieb der Turionen von Utricularia L. Osterr.
Bot. Z. 122: 15-20.
Plachno, B.J., Adamec, L., Kozieradzka-Kiszkurno, M., Swiqtek, P, and Kamiriska, I. 2014. Cy-
tochemical and ultrastructural aspects of aquatic carnivorous plant turions. Protoplasma 251:
1449-1454.
Sculthorpe, C.D. 1967. The Biology of Aquatic Vascular Plants. Edward Arnold, Ltd., London.
Winston, R.D., and Gorham, PR. 1979a. Turions and dormancy states in Utricularia vulgaris. Can.
J. Bot. 57: 2740-2749.
Winston, R.D., and Gorham, PR. 1979b. Roles of endogenous and exogenous growth regulators in
dormancy of Utricularia vulgaris. Can. J. Bot. 57: 2750-2759.
Literature review
By John Brittnacher
Bailey, T. 2015. Drosera x eloisiana, not D. x belezeana. Planta Carnivora 37(1): 42-47.
Camus (1891) described a plant he considered a hybrid between Drosera rotundifolia and D.
intermedia and named it D. x belezeana after the collector, Marguerite Beleze. Jan Schlauer ques-
tioned whether the specimen in the Paris herbarium is in fact a hybrid. He suggested to a number of
people that the specimen appears to be D. rotundifolia and a new type specimen be selected. Bailey
(2015) collected a confirmed D. rotundifolia x intermedia hybrid in the UK and designated it as the
type for the hybrid. He also proposed a new name, Drosera eloisiana. However in this situation,
current rules of nomenclature (ICN Art. 57.1) demand the preservation of the current name rather
than the creation of a new name. Stay tuned; this taxonomic drama is not yet finished. There is more
likely to be said in the future.
Camus, E.G. 1891. Note sur les Drosera, observes dans les environs de Paris. Journal de Botanique
5: 196-199.
194
Carnivorous Plant Newsletter
Hypothesis of mucilage- assisted dispersal of Drosera seeds
Robert Gibson • 5 Kristen Close ‘Cardiff Heights *NSW, 2285 • Australia • robert.gibson@
environment.nsw.gov.au
Several Drosera taxa occur in seasonally wet herbfields on the upper slopes of isolated gran-
ite outcrops in inland South Western Australia. These habitats are naturally irrigated by runoff
from adjacent rock surfaces. Many of these sundews that grow here, particularly rosetted tuber-
ous sundews {Drosera subgenus Ergaleium section Erythrorhiza) and fan-leaved sundews (D.
subgenus Ergaleium sect. Stolonifera) produce spherical seeds around 1 mm diameter that lack
obvious surface characters to readily facilitate dispersal to other granite outcrops. Yet these
sundews are common components of these habitats in the region. How then did these sundews
spread across the landscape when their seed appear to be poor candidates for long-distance
dispersal?
It has been suggested that perhaps foraging water birds may have helped spread sundew
seeds that have been entrained in mud that temporarily adheres to their feet (Lowrie 1988, pers.
comm.). Or seed may be dispersed by strong winds (Lowrie 2014: vol. 1, p. 338). Such events
have likely occurred, however another factor contributing to seed dispersal may be at play.
During fieldwork in this part of the world over the last 20 years I have enjoyed visiting granite
outcrops where large populations of sundews, such as D. bulbosa subsp. bulbosa, D. lowriei, and
D. macrophylla subsp. macrophylla occur. Curiously many individual populations of D. bulbosa
subsp. bulbosa and D. lowriei have remarkably uniform leaf size, shape, and color and which
vary noticeably in morphology from adjacent but isolated populations.
On these granite outcrops tuberous sundews often grow sympatrically with a range of other
geophytes, including the exotic Romulea rosea (Iridaceae). These habitats are frequented by a
range of birds, including Galahs ( Eolophus roseicapilla) that feed on seeds of herbs and bulbs.
During my visits I have occasionally observed the dehiscence of some Drosera bulbosa and D.
macrophylla seed directly onto bedewed leaves of the same or adjacent rosettes where the seeds
become coated in mucin (Fig. 1).
Mucin produced by the insect-trapping glands on the leaves of sundews consists largely of an
aqueous solution of polysaccharides (Rost & Schauer 1977). After desiccation and rehydration
the mucin once-again become sticky.
I propose that in addition to the water-bird transport hypothesis, that large round seeds of
some sundews have been periodically spread between granite outcrops by other birds, such as
parrots. In their search for food they have sometimes had mucin-coated Drosera seed adhere to
their bodies which they have occasionally transported to other suitable but isolated habitat. Sun-
dew seed may be collected by birds walking directly on live rosettes already with fresh seeds on
them. Or perhaps birds walk first on live rosettes, picking up mucin, then onto ground with seeds
on it. Or even perhaps birds collect older seeds with a rehydrated coating of mucin?
If correct, this mechanism increases the number of options in which chunky, relatively heavy
sundew seeds may occasionally be successfully dispersed to new areas of suitable habitat to
found new populations. Such successful dispersal events would likely occur only very rarely but
appears to be supported by the presence of greater morphological variation between, rather than
within, these isolated populations. This seed dispersal hypothesis may apply to other Drosera
taxa around the World.
Volume 44 December 2015
195
Figure 1: Drosera bulbosa subsp. bulbosa (and D. glanduligera) on a granite outcrop
near Hyden. Some seed has been shed directly onto active leaves.
Acknowledgement: I thank Allen Lowrie for discussions on the subject of Drosera dispersal that
have kept me thinking about this interesting topic.
References
Lowrie, A. 2014. Carnivorous Plants of Australia: Magnum Opus. Redfern Natural History Produc-
tions, Poole.
Rost, K., and Schauer, R. 1977. Physical and chemical properties of the mucin secreted by Drosera
capensis. Phytochemistry 16: 1365-1368.
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196
Carnivorous Plant Newsletter
Technical Refereed Contribution
Photoperiod regulates Cape Sundew ( Drosera capensis )
GLAND SECRETION AND LEAF DEVELOPMENT
Wang Dong-Hui • College of Life Science • Peking University • Haidian • Beijing 100871 • PRC
Wang Dong-Qi • Cui Yi-Wei • Yang Lu • Gu Xiao-Di • Song Wen-Fei • Li Feng • The High School
Affiliated to Renmin University of China • Haidian • Beijing 100080 • PRC • lifeng2004@pku.
edu.cn
Keywords: carnivorous plant, photoperiod, plant development, Drosera capensis.
Abstract: Cape Sundew ( Drosera capensis ), a carnivorous plant that catches flies with sticky mu-
cus, has attracted great interest among botanists and horticulture hobbyists since the Darwin era.
But little is known about how this carnivorous plant regulates morphogenesis and organ formation
to accommodate environmental changes. In this article we present the relationship between gland
secretion of Cape Sundew and photoperiod utilizing various physiological and morphological meth-
ods. We show that Cape Sundew grows faster and secretes more mucus under long days than under
short days. Under long days leaf length and the blade\petiole ratio increases, leading to increased
fly catching capacities. More importantly, in the short term, the rhythm of photoperiod causes Cape
Sundew to secrete mucus independent of photo intensity.
Introduction
As one of the most special plant groups, carnivorous plants perform photosynthesis and feed
on insects and some large carnivorous plants even prey on birds and small mammals. Darwin
believed that a carnivorous plant was one of the most astonishing phenomena in the world (Dar-
win 1875; Ellison & Gotelli 2009). Carnivorous plants are represented by more than 600 species
belonging to 20 genera (Ellison & Gotelli 2001; McPherson 2010). Before the 19 th century, the
majority of naturalists and gardeners believed that “There were no plants that could eat animals
because they had no mouth to eat or stomach to digest” (McPherson 2010). Darwin and his
son were strongly opposed by people because nobody believed the existence of carnivorous
plants. Despite the opposition, Darwin and his son fully verified by “Darwin-style research”
that Drosera rotundifolia could catch and digest insects. Carnivorous plants can be divided into
three insect-catching mechanisms: 1) catches insects by quick movement ( Dionaea muscipula ),
2) by mucus (Drosera), 3) by pit-fall traps (Nepenthes). Drosera is the most widely distributed
genus with the largest number of species and can survive not only in the Asian, European, and
American wet lands, but also in the seasonal drought regions in the Southern Hemisphere. De-
spite numerous species and huge differences in surrounding environment, most Drosera live
in a non-nutritive acid soil environment where the organic substances are slowly decomposed.
Drosera catch insects by mucus secretion. When a Drosera catches insects with its extremely
sticky mucus, its leaf will become bent to wrap the insects and form an external stomach which
secretes digestive liquid. In this process, the phytohormone jasmonic acid (JA) plays a major
role (Nakamura et al. 2013). There are also species which catch insects by both quick movement
and mucus. For instance, the tentacle of Drosera glanduligera, a sundew from southern Austra-
Volume 44 December 2015
197
lia, swiftly catapults prey onto adjacent sticky mucus-tentacles and then digest it (Poppinga et
al. 2012).
The leaves of carnivorous plants not only perform photosynthesis, but also catch insects. These
specialized leaves, however, have low photosynthetic efficiency compared with normal leaves,
which is believed to be an adaptation to carnivorous behaviors. A “cost-benefit” model was pre-
sented by Pavlovic (2010) to explain this phenomenon. Plants need to predict seasonal changes by
perceiving photoperiod signals, and then adjust their growth and development process accordingly
(Putterill et al. 1995; Kobayashi & Weigel 2007; Harmer 2009). In this paper we show that photo-
period regulates leaf growth and mucus secretion in Drosera capensis, providing new insights into
our understanding of carnivorous plants.
Method and Materials
Plant culture
Drosera capensis were transplanted into moist soil and covered with moss. For photoperiod
experiments, plants were grown in chambers under either long day (LD: 16/8 h; light intensity 3500
Lux) or short day (SD:8/16 h; light intensity 3500 Lux). For different light intensity experiments
“LD 1/2” was 1800 Lux, and “SD 2 times” was about 7460 Lux. The greenhouse humidity was 50-
70% and the temperature was kept at 25°C.
For each treatment, lengths of petiole and blade were measured on more than 3 leaves every
week (accurate to 1 mm) and blade/petiole ratio was calculated. In addition, a dissecting microscope
(Moticam 2306) was used to observe gland secretion. Both the observation and the measurement
lasted more than two months.
Scanning electron microscopy (SEM) method
Fixation: Samples were soaked in FAA fixative (100% alcohol: 50 ml; 37-40%: formaldehyde:
10 ml; acetic acid: 5 ml), vacuumed gently until the samples sank to the bottom, fixed for 12-24
hours, and the solution was changed once. Gradient dehydration: 50% ethanol 20-30 min; 70%
ethanol 20-30 min; 90% ethanol 20-30 min; 100% ethanol twice, 20-30 min each. Critical point
drying: 6 cycles. Spraying: 15 nm thickness, 90 seconds. Finally, electronic microscope photo-
graphs.
Results
Droseraceae leaf morphology
Drosera belongs to the plant family Droseraceae. There are great leaf morphological differ-
ences among different species. Drosera spatulata (Fig. IB), has spoon-shaped leaves with no
obvious boundary between petiole and blade, and its glands are in the distal part. Drosera pul-
chella (Fig. 1C) has a round blade with glands in the distal end, the proximal part is flat without
glands. Leaves of Drosera aliciae (Fig. ID) are ligulate-shaped without obvious blade and petiole
boundaries, and has glands covering all of the leaf. Drosera capensis (Fig. 1A) leaf has an obvi-
ous boundary, which was selected as the main experimental material because they were easy to
grow and reproduce. The Drosera capensis leaf can be divided into two domains (dominant): The
proximal part of leaf petiole and the abaxial end blade part (Fig. 1A and E). Glands only grow in
the blade and not in the petiole. As shown by SEM (scanning electron microscopy), a gland can
be divided into a globular head and a rod-shaped base, which is connected to the surface of the
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Figure 1: The leaf morphology of Drosera. (A) Drosera capensis, white arrow indicates
petiole, black arrow indicates blade; (B) Drosera spatulata ; (C) Drosera pulchella ; (D)
Drosera aliciae ; (E) Drosera capensis-, (F-G) Drosera capensis inflorescence.
Long day environment activates gland se-
cretion
Exposed under the LD condition for
one week, Drosera capensis grew faster
than those under SD (Fig. 2A). Leaves
were long and flat, which favor catching
insects. The gland secreted much mucus
covering the head, which was extremely
sticky (Fig. 2B). Under SD, leaves were
curly and small. There was no or very little
mucus on the gland head (Figs. 2C and
3D-F). However, the structure of gland
didn’t show any significant morphologic
difference between LD and SD, except SD
gland’s diameter is slightly smaller than
Figure 2: Drosera capensis phenotypes (A)
under LD and SD. Gland mucus secretion LD
(B) and SD (C).
blade (Fig. 3A and D). After full expansion of the leaves, glands begin to secrete mucus (Figs.
IE and 2B) and have the ability to capture insects. After a period of vegetative growth, the plant
starts flowering. Their inflorescences are
curled and gradually open during the elon-
gation process. This type of bolting could
keep flower and pollinators away from the
dangerous sticky leaves (Fig. 1F-G).
Volume 44 December 2015
199
Figure 3: SEM of Drosera capensis gland on LD and SD. Leaf on LD (A); the head
secreted mucus (white arrow) (B-C). On SD (D), the gland had no significant morphologic
difference compared with LD, but there was no mucus on the glands (E-F). The scale is
indicated by the black bar.
LD (Fig. 3B and E). The gland on SD still has the secretion function because it secreted mucus
again after it was put back to LD for one week.
LD increases the ratio of blade and petiole
The day length not only affects gland secretion in short term, but also could affect leaf morphol-
ogy in long term. The Drosera capensis , which leaf has a ratio of blade and petiole close to 1 : 1, were
put into LD and SD respectively. After two weeks, the blade gradually grew longer than the petiole
under LD. However, the plant moved to SD has a longer petiole and shorter blade compared with the
LD plant (Fig. 4A), but the full length of the leaf had no statistical difference up to six weeks (Fig.
4B). The newly developed leaves were also measured after 5 weeks. The new leaves on LD have
higher blade/petiole ratio and longer full leaf length than SD (Fig. 4C and D ).
Rhythm of photoperiod is the main factor affecting gland secretion in the short term in Drosera
capensis
Different light conditions could cause rhythm difference as well as energy difference. Under LD
condition Drosera capensis gets more solar energy, which could affect plant development in many
ways. To further investigate which aspect of photoperiod plays a more important role, a series of
experiments were performed. Drosera capensis plants were grown for 6 weeks under LD and SD re-
spectively. Then the SD plants were moved back to LD with full illumination intensity (Fig. 5C and
H) and SD with twofold illumination intensity (SD + 2X light) (Fig. 5E and J). The LD plants were
also moved to LD with half-illumination intensity (LD + 1/2 light) (Fig 5D and I). After 1 week,
plants grown under LD (Fig. 5A and F), LD + 1/2 light (Fig. 5D and I), and from SD to LD (Fig. 5C
and H) were able to secrete mucus. The plants grew under SD (Fig. 5B and G) and SD + 2X light
(Fig. 5E and J) still haven’t had any mucus. All of the results above show that it was the rhythm of
photoperiod rather than the quantity of solar energy that regulates gland secretion in the short term.
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Carnivorous Plant Newsletter
SD
A
B
•ID
n-eekl week2 week3 week4 week5 week6
so
c
o
CO
<y
cso
c
o
Cm
CO
O
D
Figure 4: Different photoperiods affect the leaf blade/petiole ratio and leaf length. (A)
Drosera capensis leaf blade/petiole ratio on LD and SD. (B) Leaf length on LD and SD
(number of leaves, N= 16-20). (C) The blade/petiole ratio of newly developed leaf on LD
and SD. (D) The newly developed leaves length on LD and SD. (* T-test, P<0.05. number
of leaves, N=18-38).
Figure 5: Photoperiod regulates Drosera capensis glands secretion independent of
illumination intensity. (A & F) on LD; (B & G) on SD; (C & H) on SD moved to LD 1 week;
(D & I) on LD moved to LD+1/2 light 1 week; (E & J) on SD moved to SD + 2x light 1 week.
Discussion
In this paper with different photoperiod and illumination intensity treatments, combined with
morphological analysis, we demonstrated that sundew (carnivorous plant) adapts to seasonal chang-
es in different photoperiod environments by regulating the quantity of mucus secretion and ad-
justing the proportion of insect-catching (leaf blade) and non-insect-catching (leaf petiole) parts.
Compared with LD it was obvious that the secretion function of glands under SD was decreased, and
leaf blade elongation was also inhibited. After switching from SD environment to LD environment,
secretion ability can be fully recovered which indicated that the morphological structure and func-
Volume 44 December 2015
201
tion of secretion were normal in both processes of growth. In LD condition, when illumination in-
tensity was decreased by half, the quantity of mucus secretion had no significant change. Similarly,
in SD condition, even when illumination intensity was increased by two times, the secreting gland
ca nn ot secrete mucus in the short term. The experimental results above indicated that the secretion
ability of the secreting gland of sundew was mainly influenced by the rhythm changes of different
photoperiods. In addition to the short term effect of mucus secretion, growing in SD environment
for a long time, the sundew had obvious phenotypes such as short and curled leaf. Moreover, the
proportion of leaf blade was less than for the LD plant.
It’s crucial for carnivorous plants whether insects can be caught. Mostly, carnivorous plants grow
in the environment where there is a lack of nutrition and cannot meet the demand of absorbing ele-
ments such as N and P by the root. Therefore, the carnivorous plants catch insects instead of root
nutrient absorption to maintain growth. The same as normal plants, carnivorous plants also forecast
and feel seasonal changes through rhythm changes of photoperiod. The glandular secretion of leaf
mucus is the only weapon for sundews to catch insects. In an environment where seasonal changes
are significant, the quantity of insects is usually rare in winter. At this time, it’s not worth consuming
too much energy to grow insect-catching organs and secreting a lot of mucus. However, in spring
and summer there are plenty of insects in the environment and sundews can secrete a lot of mucus
at this time to catch a lot of insects to meet the demand of fast growth. In addition to sundews which
can regulate mucus secretion initiatively, pitcher plants were also reported to have passive regula-
tion. When dews gather on the peristome of pitcher plants ( Nepenthes rafflesiana ) it will become
unusually smooth, which makes it easier for ants to fall and increases the opportunity to catch
insects. However, the existence of dews depends on external moisture variation (Bauer et al. 2015).
As for Venus flytrap ( Dionaea muscipula ), it also has the ability to adapt to seasonal changes. The
Venus flytrap leaf grows along the ground and the petiole of expands in winter, while the trapping
lobe which is in charge of catching insects is smaller and loses the ability to close, which makes it
hard to catch insects (unpublished observation).
Compared with normal plants, carnivorous plants need to prioritize between photosynthesis and
getting nitrogen resources. Photoperiod regulates the mucus secretion and leaf morphogenesis of
sundews, which provides a new research direction to study this issue. Since Darwin’s day, carnivo-
rous plants have been studied extensively. The results obtained by modern biology will help people
to further understand carnivorous plants.
References
Bauer, U., Federle, W., Seidel, H., Grafe, T.U., and Ioanou, C.C. 2015. How to catch more prey with
less effective traps: explaining the evolution of temporarily inactive traps in carnivorous pitcher
plants. Proc. Royal Soc. London B: Biol. Sci. 282:20142675.
Darwin, C. 1875. Insectivorous Plants. John Murray, London.
Ellison, A.M., and Gotelli, N.J. 2001. Evolutionary ecology of carnivorous plants. Trends in Ecol.
& Evol. 16(11): 623-629.
Ellison, A.M., and Gotelli, N.J. 2009. Energetics and the evolution of carnivorous plants — Darwin’s
‘most wonderful plants in the world’. J. Exp. Bot. 60(1): 19-42.
Harmer, S.L. 2009. The circadian system in higher plants. Ann. Rev. Plant Biol. 60: 357-377.
Kobayashi, Y., and Weigel, D. 2007. Move on up, it’s time for change — mobile signals controlling
photoperiod-dependent flowering. Genes Dev. 21(19): 2371-2384.
McPherson, S. 2010. Carnivorous Plants and their Habitats. Redfern Natural History Productions
Ltd., Poole, GB.
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Carnivorous Plant Newsletter
Nakamura, Y., Reichelt, M., Mayer, VE., and Mithofer, A. 2013. Jasmonates trigger prey-induced
formation of ‘outer stomach’ in carnivorous sundew plants. Proc. Royal Soc. B: Biol. Sci. 280
(1759): 20130228.
Pavlovic, A. 2010. Spatio-temporal changes of photosynthesis in carnivorous plants in response to
prey capture, retention and digestion. Plant Signal Behav. 5(11): 1325-1329.
Poppinga, S., Hartmeyer, S.R., Seidel, R., Masselter, T., Hartmeyer, I., and Speck, T. 2012. Catapult-
ing tentacles in a sticky carnivorous plant. PLoS One 7(9): e45735.
Putterill, J., Robson, F., Lee, K., Simon, R., and Coupland, G. 1995. The CONSTANS gene of Ara-
bidopsis promotes flowering and encodes a protein showing similarities to zinc finger transcrip-
tion factors. Cell 80(6): 847-857.
THE
ICPS Seed Bank
an exclusive member benefit
The International Carnivorous Plant Society offers its members exclusive access to a variety of
carnivorous plant seeds. Seeds are ordered online at the ICPS Store:
http://icps.clubexpress.com
The Seed Bank cannot exist without seed donations. Information about growing carnivorous
plants from seed and donating seeds to the Seed Bank are at the ICPS public web site:
http://www.carnivorousplants.org
If you do not have access to the Internet, please send seed order form requests to:
International Carnivorous Plant Society, Inc.
2121 N. California Blvd., Suite 290
Walnut Creek, CA 94596-7351, USA
JOE GRIFFIN, Seed Bank Manager, joe@carnivorousplants.org
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Volume 44 December 2015
203
Technical Refereed Contribution
Second brief piece of information about the species status of
Utricularia cornigera Studnicka
Miloslav Studnicka • Liberec Botanic Gardens • Purkynova 630/1 • CZ-460 01 • Liberec • Czech
Republic • botangarden@volny.cz
Keywords: Utricularia cornigera, bladderwort, hybrids, bladders, traps.
Abstract: Hybrids of Utricularia nelumbifolia x U reniformis (and vice versa) were raised, and the
bladders of adult individuals taken out of the soil were observed. With their long antennae they re-
semble their parents, yet they differ noticeably from the identically situated bladders of U. cornigera
that has characteristic short antennae. Therefore, the morphology of the bladders does not support
the hypothesis of a hybrid origin of U. cornigera.
Introduction
The seedlings from the artificial cross-breeding of Utricularia reniformis x U. nelumbifolia (and
vice versa) documented in CPN 2 years ago (Studnicka 2013) have become adult plants, and thus
it was possible to document the traps of the hybrids. In this study, a comparison is made with both
the parental species and with U. cornigera, for it is a species related to both cross-bred species. The
species U. cornigera and U. reniformis are similar to each other with their kidney-shaped leaves. The
species U. cornigera and U. nelumbifolia have symbiotic relationships to host rosette-forming plants
(Studnicka 201 1). All the three species are endemic to south-eastern Brazil.
Material and Methods
The hybrids described in the previous brief information (Studnicka 2013) were investigated.
These plants have been raised and continue to be kept in the Liberec Botanic Garden. Stolons with
bladders were removed from the soil and placed into a small bowl with water. The live material was
observed and photographed with a microscope at 16-times magnification. The mounts were made
in such a way that the antennae were as visible as possible. In the case of U. nelumbifolia, traps
from an aquatic environment were observed as this species does not grow in soil. Traps from a soil
environment were documented and compared in the case of all the other species and hybrids. In each
case, 1 0 mounts were observed and as no significant variability was ascertained, one representative
photograph at a time is included in this article.
Results and Discussion
Protrusions growing out of the throat towards the front of the trap mouth, referred to as antennae
(Taylor 1989), are usually considered (inter alia) to be a characteristic feature of each species of the
genus Utricularia. Their shape is apparently associated with the strategy of hunting microscopically
small prey and with some specialization (Lloyd 1942). Soil traps specialize in soil microfauna of
various composition, whereas water traps are adapted to hunting zooplankton. With respect to the
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Carnivorous Plant Newsletter
species U. reniformis, the difference between soil and water traps (if they are created at all) is more
in the size of the bladder than in the shape and proportionate length of the antennae. By contrast, U.
cornigera is characterised by marked dimorphism of the traps: water traps (Studnicka 2009) have
relatively long antennae; soil traps, by contrast, also displayed herein (Fig. 1), have very short ones,
reduced to small “horns” ( cornigera = horned).
In the species U. reniformis and U. nelumbifolia no traps with short antennae are known at all,
and the antennae always go beyond the stalk of the bladder (Fig. 2). It is also the same case with their
FI hybrids created by reciprocal cross-breeding (Fig. 3).
Conclusion
The soil traps of the hybrids created by the artificial cross-breeding of U. nelumbifola and U. re-
niformis do not resemble the soil traps of the relative U. cornigera at all. There is no predisposi-
tion towards short antennae either in the hybrids or in the parental species. This implies that this
Figure 1 : Very short antennae on the soil vesicle of Utricularia cornigera.
Figure 2: Very long antennae on the bladder of Utricularia nelumbifolia (left); and a soil
vesicle of Utricularia reniformis, where the antennae extend to the stem (right).
Volume 44 December 2015
205
Figure 3: Very long antennae on the soil vesicle of Utricularia nelumbifolia 9 x U. reniformis
(left); and very long antennae on the soil vesicle of Utricularia reniformis 9 x U. nelumbifolia
(right).
characteristic feature present in the species U. cornigera has apparently developed by evolution.
It is not possible for the difference between the hybrids and U. cornigera to have been caused by
environmental effects because all the plants had identical conditions. The above investigation again
refutes the hypothesis of a possible hybrid origin of U. cornigera, which was a stimulus for creating
the hybrids documented herein.
References
Lloyd, F.E. 1942. The Carnivorous Plants. Reimpr. 1976, Dover Publications, Inc., New York.
Studnicka, M. 2009. Brazilian bladderwort Utricularia reniformis is a blend of two species. Thaiszia,
Kosice 19: 131-143.
Studnicka, M. 2011. Surprising phenomena in the life strategy of Utricularia cornigera in Brazil.
Thaiszia, Kosice 21: 37-43.
Studnicka, M. 2013. Brief information about the species status of Utricularia cornigera Studnicka.
Carniv. PI. Newsletter 42: 15-18.
Taylor P. 1989. The genus Utricularia - a taxonomic monograph. Kew Bull. Additional Ser. XIV,
Royal Bot. Gardens, Kew.
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HOW HUNGRY ARE CARNIVOROUS PLANTS? An INVESTIGATION INTO THE
NUTRITION OF CARNIVOROUS PLANT TAX A FROM THE
Kimberley region of Western Australia
Laura Skates and Adam Cross • The University of Western Australia, Stirling Highway, Crawley,
Perth 6009, WA, Australia • and • Kings Park and Botanic Garden, Fraser Avenue, Kings Park,
Perth 6005, WA, Australia • Laura.Skates@bgpa.wa.gov.au
The Project
The pristine Kimberley region in the north of Western Australia is a global centre of carnivorous
plant diversity, well known for its abundance of Drosera (ca. 20-30 species), Byblis (four species),
and Utricularia (at least 30 species). New taxa continue to be discovered here on a regular basis. As
carnivorous plants tend to prefer sunny, moist and nutrient poor environments, the tropical monsoon
climate and poor soil fertility of the Kimberley region have allowed for significant diversification of
these carnivorous plant genera. The Kimberley sits on a geologically ancient landscape, with natu-
rally old and well-weathered parent rock material and highly leached soils, thanks in part to very
high levels of rainfall during the summer monsoon. From May to October, the Kimberley region ex-
periences a hot and often fire-prone dry season, which is followed by a short but unpredictable wet
season from November to April. During the 4-5 month wet season it is not uncommon for the region
to experience frequent lightning storms, intense tropical cyclones and large flooding events, with
rainfall in northern coastal regions during this short period frequently exceeding 2000 mm (around
80 inches). Subsequently, access during the wet season can be extremely difficult, with many areas
simply remaining inaccessible until the cessation of seasonal rains.
The nutrition of carnivorous plants is an endlessly fascinating topic, especially given that these
plants are able to absorb supplementary nutrients by attracting, capturing, and digesting insect prey
with their specially modified leaves. Many aspects of the nutrition of carnivorous plants have been
studied in great detail, with Schulze et al. (1991) pioneering the use of stable isotope techniques to
determine how reliant West Australian species were on capturing insect prey to meet their nutritional
needs, as opposed to gaining nutrients through root uptake. While this research shed some light on
twelve Drosera species from the southwest region of Western Australia, there has been no similar
research conducted on the carnivorous taxa of the Kimberley region. This is where my (LS) PhD
project comes in, based at the University of Western Australia and Kings Park and Botanic Garden,
Perth, Western Australia.
In order to gain an understanding of the nutrition of a wider variety of the carnivorous plant
taxa that occur naturally throughout Western Australia, we proposed to expand upon the work of
Schulze et al. (1991), with a broader range of species surveyed and greater replication. We began
this project with a field trip to a remote area of the Kimberley, to collect samples under scientific
license of carnivorous plants, non-carnivorous reference plants, potential insect prey, and soil.
These samples will be used to determine nutritional differences between carnivorous plant species,
and compare this to underlying site characteristics. Our team’s research, and particularly the costs
associated with remote field study, is funded by grants from Murdoch University, Kings Park and
Botanic Garden, the Friends of Kings Park, and the International Carnivorous Plant Society. What
follows is an account of our journey to this wonderful part of Australia and how we went about
making our collections.
Volume 44 December 2015
207
The Journey
To be perfectly honest, in the weeks leading up to this field trip, I was a little apprehensive. The
last time I’d been on a serious field trip was nearly two years prior, but add to that the fears that many
people associate with the Australian outback: ending up lost in the vast remoteness of the Kimberley
(some 423,5 17 km 2 of predominantly uninhabited wilderness), suffering dehydration or heat shock,
being poisoned by snakes, waking up covered in spiders, or eaten by a giant crocodile. In the wise
words of Russell Coight “out here, survival is the name of the game. Only it’s not a game; it’s deadly
serious”. With a lot of preparation and a fair amount of luck, we survived our own “All Aussie Ad-
venture” and now it’s time to tell the tale!
Our journey began in late March, towards the end of the Kimberley’s wet season, in the town of
Kununurra. Here, sadly, the invasive cane toad species Rhinella marina L. (Bufonidae) has made
its mark. For those that may not be aware, the cane toad was introduced to northern Queensland in
1935 in an ill-fated attempt to eradicate problematic cane beetles, and has been steadily working its
way across the monsoon tropics ever since. Unfortunately, this plan has resulted in much of our na-
tive fauna falling victim to the poisonous cane toads. This was my first time seeing these creatures
in person, and, I’ve got to say, they aren’t pretty! Some other wildlife we were much happier about
getting acquainted with included the TaTa lizard ( Lophognathus temporalis ), so called for the wave
goodbye it does with its front legs after racing away from threats, and the beautiful big boab trees
(Adansonia gregorii ). This is definitely a place that I would like to see a bit more of one day, and
maybe even climb to the top of the local hill, Bob’s Knob! However, after one night’s stay, we were
off the next morning to our remote north Kimberley field site; a large pastoral station surrounded by
pristine bushland, where we would be spending the next week.
Given that our field site is so very remote and the roads are inaccessible during the wet season, the
only feasible form of transport was to charter a flight on an aptly named 12-seater Cessna Caravan (Fig.
1). We placed our luggage in amongst the packages ready to be delivered to the many remote stations
along the way, and strapped ourselves in. Seeing the Kimberley from a bird’s eye perspective was a defi-
nite highlight, with my favourite view being that of the Pentecost and Durack River delta, with its winding
pathways and incredible colours (Fig. 2). However, it was certainly nice to find ourselves landing at our
final destination, returning to solid ground and breathing some of the freshest air I’ve ever encountered.
Upon landing at the station, we were greeted by its caretakers, Wendy and Bruce, and their dog
Bonnie, a beautiful Ridgeback-
Dingo cross. First of all, I cannot
thank the caretakers enough for
their hospitality and generos-
ity, and I’m also very grateful for
Bonnie the dog, who became our
best friend and fieldwork com-
panion for the week (Fig. 3). We
were given a quick tour of the sta-
tion: the caretakers’ and owner’s
homes had beautiful gardens with
fruit trees; the nearby shed was
fully equipped to make sure every-
thing ran smoothly, including the
quad bikes we would be using to
Figure 1: Our charter Cessna Caravan.
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Carnivorous Plant Newsletter
travel between sites each day; and
the dongas (small portable rooms)
where we would be sleeping were
located right next to showers and
cooking facilities. For a moment,
it was easy to forget that we were
staying out in the middle of no-
where. . . that is, until we found the
frogs hanging out in the toilet and
geckos crawling in the cupboards!
Wildlife was not uncommon, with
the howls of a dingo ( Canis lupus
dingo) in the distance, bats flying
about the garden at night, a poison-
ous taipan ( Oxyuranus scutellatus
scutellatus) in the shower, and a
big black whip-snake ( Demansia
papuensis ) that was spotted near
our dongas! These surprises with-
in the pastoral station made the ex-
perience all the more exciting, and
left us wondering what surprises
would await us out in the pristine
bushland. We got ourselves settled
in for a good night’s sleep, ready
for the proper fieldwork to start
bright and early the next morning.
The Fieldwork
Given we would be conducting our fieldwork in a remote and somewhat dangerous environment,
safety was obviously our number one priority. Firstly, to avoid getting lost and to keep track of where
we were in the landscape, our fieldwork leader Dr. Adam Cross carried a GPS and EPIRB at all times.
Secondly, to keep safe from the hot and sunny environment, we always took plenty of water. Thirdly,
we were covered from head to toe with wide-brimmed hats, long-sleeved clothing, hiking boots,
sunglasses, and lots of sunscreen. Finally, to protect ourselves from snakes hiding in the tall grasses,
we wore knee-high gaiters. Of course, our fieldwork companion Bonnie the dog roamed about the
landscape without any worries, as if it were her personal kingdom; drinking from the rivers, resting
in the shade, and chasing away any form of wildlife that we encountered, including a young dingo, a
big Monitor lizard ( Varanus panoptes ), and a stubborn group of feral cattle ( Bos taurus).
In order to get to our sites, we each drove a quad bike loaded up with all of our equipment and
water, and made our way through the tall grasses, over rocks and dead tree branches. Riding about
on those quad bikes was a whole lot of fun, and it’s something I really miss now that I’m back in
Perth and not out in the field! We would always stay on one track so as to reduce disturbance to the
natural landscape, with Adam leading the way. Unfortunately for Adam, this meant he was pelted
with spiky Sorghum grass seeds far more than the rest of us, and at one point managed to drive
Volume 44 December 2015
209
through a large spider’s web and ended up with both the web and the spider wrapped around his
face! Bonnie often ran at the head of our quad bike conga line, but always doubled back to check
on the last person and make sure the whole pack was okay. Over the course of the week Bonnie ran
nearly 100 km, so it’s no wonder that at the end of each day she would stubbornly request a lift back
on the back of the last quad bike through the station’s gate. Driving back to the station slowly, with
Bonnie curled up behind me, was the best way to end a tough day out in the field!
Over the course of the week, we collected samples of more than ten different Drosera species
and two Byblis species, across nine different sites. We also encountered several Utricularia species,
although these were not collected as they were outside the scope of my PhD research. Unfortunately,
there will have been several species that we missed, as many are quite transient in nature and only
present on the landscape for a few weeks each year. Some are expected to flower for only a few days,
especially given the relatively dry wet season this year. For the species that we could find, samples of
leaf material were collected at each site, along with samples of non-carnivorous plant species to be
used as a nutritional reference. Samples of insects and soil were also collected at each site, as these
are the two major sources of nutrients for the carnivorous plant species. All of this was very exciting
for me, not only to be successful in making my first collections for my research, but also to see such
an incredible array of carnivorous plant species, each with different and simply beautiful life-forms.
Many of the carnivorous plants sampled occurred on shallow sands in some variation of an open herb
field, surrounded by tall Sorghum grasses and a few Eucalyptus trees, adjacent to the aprons of sand-
stone outcrops. Open fields of Byblis filifolia were very common and occurred at seven out of nine sites,
always accompanied by a handful of other carnivorous plant species such as B. rorida, Drosera banksii,
D. burmannii, D. cucullata, D. dilatato-petiolaris , D.fragrans, D. glabriscapa, D. paradoxa, and D. sub-
tilis, as well as several yet-to-be-formally-described Drosera taxa. Several of these species were easy to
locate, with their bright purple and pink flowers, such as Byblis fdifolia and Drosera fragrans. However,
for many of the smaller Drosera taxa, such as D. banksii and D. burmannii, it was necessary to get down
on hands and knees in the mud and push back the low herbs and grasses to find the dewy plants hiding
beneath. As you might expect, we would often find a greater abundance and diversity of carnivorous
plants at the edges of pristine sandstone creeks (Fig. 4) running through the herb lands, where soils were
moister. In these areas, D. banksii, D. cucullata, and D. paradoxa in particular were more common.
While driving our quad bikes from one site to another, we stumbled upon a particularly interest-
ing patch of herb land, where we
spotted a different Drosera spe-
cies. Spread like a carpet along the
dry soil of this sandy herb land was
Drosera ordensis, a gorgeous pe-
rennial species in which the white,
hairy petioles contrast strongly with
the blood red trapping leaves (Fig.
5). This was the only carnivorous
plant species found growing in this
area; perhaps the sand was too dry
for the predominantly annual spe-
cies that we had previously found
on more moist soils. Another reason
as to why this site was of particular
interest was the presence of a nearby Figure 4: Sandstone creek running through herb lands.
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Carnivorous Plant Newsletter
Figure 5: Drosera ordensis.
cave painted with Aboriginal rock
art. Indigenous Australians have
occupied the Kimberley region for
nearly 40,000 years, and continue to
be the traditional owners of the land.
Many Aboriginal groups still prac-
tice traditional law in this region, as
part of one of the world’s oldest con-
tinuous cultures. We were incredibly
lucky to have the opportunity to see
this ancient artwork, and it is some-
thing that I will not soon forget.
One of the most exciting days
on the field trip by far required us
to cross a large river to get to our
field site (Fig. 6). That’s right, we
stripped down to our bathers, low-
ered ourselves into the murky wa-
ters of the Kimberley, and crossed
our fingers that there would be no
crocodiles! Our fieldwork leader
assured us that it would be perfect-
ly safe; usually, crocodiles don’t
come this far inland. Even if they
did, this particular area of the river
was too shallow and rocky for
their liking and located between
two waterfalls, which crocodiles
tend to avoid at all costs. Of course
this just made me think of the pos-
sibility that a crocodile could have
somehow made its way this far in-
land, got itself stuck between these
two waterfalls, become enraged by
the rocks scraping against its belly,
and would be just about ready for
a tasty meal. Crikey!
It was very reassuring that
Bonnie jumped in the river with-
out a care in the world, and swam
back and forth the whole way
while waiting for us to get our
equipment ready. This was the
real challenge: transporting all of
our sampling gear, hiking boots, lunch, and expensive cameras across the river, without them all
becoming soaked or lost at the bottom of the murky waters! We placed everything into rubbish bags
Figure 6: Our crossing at the Morgan River.
Volume 44 December 2015
211
and big plastic crates, which we floated out in front us as we swam the distance, Bonnie by our side.
Luckily, we made it across the river without any harm and without any loss of equipment. I’m not
going to lie, I felt a bit like Crocodile Dundee!
Once we’d made it to the other side of the river, the adventure was not over. We still had to trek our way
across the sandstone and woodland and collect our samples. After a somewhat rainy lunch with a beautiful
view, we found ourselves trapped under a fast approaching lightning storm. In such a remote place, light-
ning can be a big problem, as fires can be started quite easily. With our equipment, including my metal
pole with an insect net attached to the end, we were basically a beacon for any stray lightning that might
occur. We hurried off to find shelter under a large boulder overhang, to keep us (and Bonnie!) safe and dry.
Once the storm had passed, we were able to resume our work, and collected a variety of species
including Byblis filifolia, Drosera glabriscapa, D. serpens, and D. subtilis. The rain continued to drizzle
over us all day, making it quite difficult to take notes on wet paper, and leaving us soaked to the bone. As
the daylight started to fade, we began heading back towards the river crossing area and prepared ourselves
for the swim back to the other side. Floating our crates of equipment across was even more difficult this
time around, thanks to the extra weight of all of our samples, but we made it in the end! While this day
on the ficldtrip was definitely the most exciting, we were all glad to be returning to the station to dry off.
On our very last day of sampling we ventured into some swampy blacksoil areas by the roadside
in the hopes of finding a few species that had been quite elusive throughout the earlier days of the
trip. Success! We found Drosera hartmeyerorum, D. nana and Byblis liniflora growing in the shade
of other herbaceous plants, small shrubs, and Eucalyptus trees, as well as the more prevalent species
D. banksii, D. burmannii, and D. fragrans. Many of these species grew right up to the edge of the
roadside, where vegetation began to thin out, perhaps exploiting the higher light available. Having
collected as many different species as we possibly could, we returned to the station and began the
arduous task of packing away all of our equipment and samples in preparation for the long journey
home - a job that lasted well into the early hours of the next morning.
Final Thoughts
Once the trip had come to an end, I was able to reflect on the success of the field work, the dif-
ficulties involved in the sampling process, and the exciting adventurous aspects that we had the
privilege to experience. Over the course of one week, we were able to get a significant amount of
sampling done for my PhD project: nine different sites, collections of nearly 20 different carnivorous
plant species, a total of 250 plant samples (including the non-carnivorous plant samples for refer-
ence), 30 collections of potential insect prey, and about 5 kg of soil. Through this process, I was also
able to determine the best methods for collecting, sorting, and labelling my samples, which will come
in very handy when I go to collect other carnivorous plant species in the southwest corner of Western
Australia - an even more exceptionally biodiverse region harbouring more carnivorous plants than
anywhere else on the planet. The next step will be to analyse and compare all of the plant, insect,
and soil samples, to determine whether there are differences in the nutrition of species from different
families and from different geographic locations. Until then, I feel extremely lucky to have been able
to see such a great range of the native fauna and flora that makes the Kimberley region of Western
Australia so unique, and I hope I can return to this beautiful part of our country again one day soon!
References
Schulze, E.-D., Gebauer, G., Schulze, W., and Pate, J.S. 1991. The utilization of nitrogen from insect
capture by different growth forms of Drosera from Southwest Australia. Oecologia 87(2): 240-246.
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Carnivorous Plant Newsletter
New cultivars
Keywords: cultivar, Drosera intermedia ‘Eclat’, Dionaea ‘Coquiton’, Nepenthes ‘Guillermo Reyes’
Drosera intermedia ‘Eclat’
Submitted: 31 August 2015
Drosera intermedia ‘Eclat’ was found in August 2012 among a full container of D. intermedia
of wild type plants (Fig. 1 left) obtained from Cedric Azais from which the cultivar developed (by
mutation). Unlike the typical form, Drosera intermedia ‘Eclat’ has a lack of red coloration (Fig. 1).
Otherwise, the plant is similar to D. intermedia.
The name “Eclat” comes from the brightness of the mucilage.
I have successfully propagated the plant by seed and leaf cuttings.
— Arnaud Schram • 3 rue bartholdi • 68320 Fortschwihr • France • schram.a@live.fr
Figure 1: Drosera intermedia ‘Eclat’ surrounded by typical reddish Drosera intermedia
(left) and a clump of Drosera intermedia ‘Eclat’ (right).
Volume 44 December 2015
213
Dionaea ‘Coquiton’
Submitted: 24 August 2015
Dionaea ‘Coquiton’ is totally green but can verge on yellow. It is prostrate and compact, with
arched traps, reminding one of Dionaea ‘Cudo’. The petiole is short and large and sometimes there
is an excrescence on it. The teeth are short, stocky, the tip of the teeth is curved and/or deformed,
bringing the tentacles of Drosera to mind, and there are intermediate microteeth (Figs. 2 & 3).
The name Dionaea ‘Coquiton’, coined 23 September 2014, is a combination of the names of the
parents: Dionaea ‘Coquillage’ x Dionaea ‘Triton’. The plant should be reproduced only be vegeta-
tive means to ensure that its unique characteristics are maintained.
— Alexandre Letertre • 275 route de la Charite • Lieu-dit La Gauthierie * 58130 Saint Aubin Les
Forges • France • pygO@hotmail.fr
Figure 2: Dionaea ‘Coquiton’ plant.
Figure 3: Arched trap and the short deformed teeth of Dionaea ‘Coquiton’.
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Carnivorous Plant Newsletter
Nepenthes ‘Guillermo Reyes’
Submitted: 21 August 2015
Nepenthes ‘Guillermo Reyes’ is a seed grown Nepenthes platychila obtained from Borneo Exot-
ics. I have grown this plant for the past 5 years and have not seen another N. platychilla quite like it.
I named this special plant Nepenthes ‘Guillermo Reyes’ on 10 July 2015.
Leaves of this plant are covered in short, bronze-colored hairs. The new leaf emerging from the
terminal node will often appear completely bronze in color. There is a distinctive bronze line begin-
ning at each auxiliary node, extending through the mid-rib of the leaf (Fig. 4).
Lower pitchers are green, heavily blotched with red and purple, and have a red striped golden
peristome (Fig. 4). Upper pitchers are absolutely fantastic, large, and robust with a similar blotched
pitcher body as the lower pitchers, however, the peristome flares out quite far, and is covered in
hundreds of ruby red colored stripes (Front Cover).
This cultivar is named after Guillermo Reyes, a long-time friend and excellent Nepenthes grower
who has dedicated his life to this hobby.
— Axel Bostrom • 1449 Maple Avenue • Santa Rosa • California 95404 • axelbostrom24@gmail.com
Figure 4: The new leaf emerging from the growth point appears completely bronze (left);
bronze hairs make a very obvious line down the mid rib on each leaf (center); and lower
pitcher of Nepenthes ‘Guillermo Reyes’ (right).
Volume 44 December 2015
215
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216
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